So in this game, Pakistan lost the toss so India got to choose whether to bat or bowl first.
Well that would give India an exact score they needed on the board when it was their turn to bat.
Pakistan scored 338 in the 50 overs allotted to them and dropped 4 wickets.
This was a record score for a 50 Over Final and put a lot of pressure on India, particularly when Pakistan's strength is bowling.
A quick Google will give you a good explanation with varying levels of detail.