This area has the Giant who is carrying the Magic Chest. There are two ways you can deal with the Giant in order to get the chest he is carrying.

First and highest scoring is to tier him out. There are two ways to do this: walk around and avoid him or be invisible. The Giant isn't that fast, so you should be able to walk circles around the tree and avoid him. The easier route, which works just as well, is to use the Magic Ring from Elf in E8 and be invisible. In either case, the Giant will tire after about 20 seconds of chasing after/looking for you and fall asleep. When he does, he'll drop the chest he's carrying.

The other method for getting the chest involves taking down the Giant. You'll need a sling shot for this, which can be found in the cloudland here. You will also need some pebbles from beside the lake in A6. Hopefully you have these before getting to this point. After you have the slingshot, enter the screen and as quickly as possible, use it on the Giant. He'll fall down and drop the chest.

One you have the Magic Chest, you're work in the clouds is over. To get the points, make you pick up the slingshot even if you don't use it.