Mana Games

i can understand power but consistency and precision is confused me

Precision influences the precision of your strike. Look the aiming visual helper to understand the effects.
Usually, u need to have your precision about the same level than your power, coz the effect depend of the relative difference between the 2 skills.
ie: Power at 40% & Precision at 50% will give u the same precision for ur strike than Power at 80% & Precision at 90%.

Consistency determines what is the level of ball difficulty u can handle before losing precision & before losing control completely.
ie: the higher ur consistency is, the more u can advance in the Danger Zone without trouble (but even at 100%, it's still not more than 1m or so)

ok. then what about "topspin"? i think i learnt it from TEM but right now i totally forgot

Top Spin is the rotating effect given to the ball on each strike. The higher it is, the more curved the ball's trajectory will be.
For example, Nadal always puts a lot of topspin in his strikes...

that means topspin is more effective on slow or fast courts?

on slow court, coz it makes the high rebound even higher.