If you're trying to find Shadow of the Colossus fruit you got 128 pieces to find if you want them all. That's not essential to max out your health, but if you're after them all prepare to see a lot of trees. Although in the PS4 version you don't actually need to collect everything now, that was a old PS3 trophy.
As we mentioned the main point of finding fruit is to increase your health so you can tackle harder colossus with a little bit of a safety blanket. In the map below we've marked the locations of all of them so you can find it all more easily. To get them just use your bow and arrow to shot them down, and make sure you don't miss any.
Here's the map which you can click to see bigger.
There's also 48 pieces of Forbidden Fruit at the top of the Shrine of Worship that will actually reduce your HP bar permanently, so save around that to avoid losing your gains forever. There is a trophy for that but seeing as you'll need maxed out Stamina to reach the roof it's not one you can just nip and get quickly.
You can make life easier by getting the Fruit Map but that requires defeating 10 colossi in normal time attack mode, which you can only access once you've finished the game once. So , handy if you're planning to 100% everything but you'll be in for the long haul if try it.