There are several important information's that are given in the question. First thing to do is note down those information's so that every information is specifically in hand while getting to the required answer.
Mass of the softball = 0.5 kg
Force at which the softball hits the glove of the catcher = 25 newton
Let us assume the acceleration = x
We already know that
Force = Mass * Acceleration
25 = 0.5x
x = 25/0.5
= 250/5
= 50 m/s^2
So the acceleration of the softball is 50 m/s^2