A ball is kicked and flies from point P to Q following a parabolic path in which the highest point reached is T. The acceleration of the ball is?

We won't do your homework for you. However, Google "acceleration" for a lot of formulas. You will not find any answers without having some more data.

Since we do not know the distance between P and Q or the height of T there is no formula that can solve this issue.

Hint: what force acts on the ball while it is in flight? What acceleration does that force cause in all objects that are in free fall?