Separate the things that you want to keep and the things you want to get rid of.
Put the things you want in one pile and the things you don't (want) in another.
Separate the things that you want to keep and the things you want to get rid of.
「要るものと要らないものを分けて。」
separate は「分ける・区別する」という意味です。
Put the things you want in one pile and the things you don't (want) in another.
「要るものはこっちに重ねて置いて、要らないものはそっちに置いて。」
in one pile で「一つの山(積み重ねたもの)」
ご参考になれば幸いです!