Question

Usually a fielder in a cricket match moves his hands in the direction of motion of cricket ball after taking the catch give reasons

Answer 1

He allows the ball to move more because the forcr applied by the ball would be less then.So he won't get hurt.
Hope it helps!

Answer 2

Usually a fielder in a cricket match moves his hands in the direction of motion of cricket ball after taking the catch to decrease the impact of the ball as it comes with a very high velocity.

If the fielder doesn’t move the hand towards the direction of the ball, then the ball, with high velocity will tend to come out of the hand of the fielder.