In this article written by Frisco you can read about player attributes and their meaning. You won't have any doubts after this.

Hope you will enjoy reading! 

Technical attributes

Corners:
Well... The ability to take corner kicks!
Crossing:
The ability to put the ball where he wants in the opposition area while crossing.
Dribbling:
The ability to fool the oposition in one on ones. Notice that dribbling alone doesnt make a good dribbler. He would need agility, acceleration, etc.
Finishing:
Finishing is to the striker as dribbling is for the dribbler. Its the ability to shoot the ball behind the net. A good striker need other things besides finishing, like composure, etc.
First Touch:
I think about it as how well the player will receive a pass. A player with low First Touch may have the ball boucing off his feet while receiving a pass. On the other hand, a player with hight first touch will have the ball practically glued to his feet when receiving the pass.
Free Kicks:
Same as penalty taking, but for free kicks taking. Other attributes influence actual free kicks taking, though.
Heading:
The ability to direct the ball using the head. This doesn't mean that the player will win headers more frequently. For this to happen he would need strength, positioning or off the ball, bravery, etc.
Long Shots:
Player with good attribute here have ability to score long range goals. Thats all.
Long Throws:
I never gave much importance to this one, but its self explanatory, I guess. But players with high Long Throws on throw ins.
Marking:
Iis only for man marking, since for zonal marking we would have positioning. Notice that in order to mark a fast, agile player, you also need a fast, agile defender.
Passing:
How well the player can pass the ball. Note that this is only about the technique. A playmaker would also need decisions, creativity, etc. Its the player accuracy to pass the ball.
Penalty taking:
The Ability to take a penalty kick. Other attributes may also influence the penalty kick.
Tackling:
The ability to take the ball of the feet of the oposition.
Technique:
The overall skill of the player with the ball on his feet. Its a must for players who dribble often, but it also influences passing and shooting.

Mental attributes

Aggression: How incisive the player is in his tackles. An aggressive player will try more tackles and will mark more closely. A player with low aggression will play further back, will be more selective with his tackles, etc.

Anticipation: Players with good anticipation  read th well and you can expect from this player to cut many opposition passes and attack's.
Bravery:
The courage to go for 50-50 tackles, make diving headers. To risk a broken leg in order to acomplish something. Note that Bravery and Work Rate are closely related: If the player has high Work Rate and Bravery then you gut yourself a soldier.
Composure:
The player is in a tense situation. Can he keep his nerves?
Concentration:
How focused the player is in the game. Its his consistency during the game. A player with low concentration may create some great plays and give in the match the other minnute.
Creativity:
Its about knowing where to pass the ball. Nothing more. Look for passing and decisions also for a good midifield playmaker.
Decisions:
Its about making the right decision.
Determination:
The player will not give up. Its related to the current score, supporters instance and time left to play. A player with high determination will ignore those three factors and keep playing to the end of the game. A player with low determination will give up easily. It is also an importanf attribute off the field (training, recovering from injuries, etc.)
Flair:
This player will dribble a lot and he will make crowd happy with his movements.
Influence:
Its The attribute for the captain. Good players with high influence will make things work and the players will play better. Notice that a dirty, aggresive player with high influence is a bad bad thing...
Off the ball:
How well the player positions himself when atacking. Note that one thing is positioning well (off the ball), another is receiving the pass (first touch) and another is making the goal (finishing, composure).
Positioning:
How well the player positions himself defensively. This is used when the player is zonal marking.
Teamwork:
If the player will focus his plays on the tem, rather on himself. That means that he will look out for passes more often, cover for a fellow player, get close to support an atacking one, etc.
Work Rate:
How hard working is the player, normally, during a match. Does he give 100%? Does he have willingness to go after the ball and win? Someone here os the board defined it as "Hustle". Do not mistake it with Determinations, which is how well the player will perform in an adverse situation ( basically, the team is losing and you need to score ). Will he still try to fight and change the score.

Physical attributes

Acceleration:
How fast the player can up his speed.
Agility:
The ability to turn his body fast and make quick movements.
Balance:
The ability to stand up while other player try to tackle or push them.
Jumping:
This is related with heading. In order to get to the ball in the air, the player will have to...jump well.
Natural Fitness:
Its about how fast he recoveres from injuries and for how long he will keep playing (age).
Pace:
The maximum speed the player can get to.
Stamina:
How long he can keep playing until getting tired.
Strength:
The overall physical strength of the player. This ability should not be overlooked, as it is usefull for challenging balls in the air, on 50-50 challenges, for a striker to stan up in a fight with the defense, etc.