A heap of things is a pile of them, especially a pile arranged in a rather untidy way.

If you heap things somewhere, you arrange them in a large pile.

If you heap praise or criticism on someone or something, you give them a lot of praise or criticism.

Heaps of something or a heap of something is a large quantity of it.

Someone who is at the bottom of the heap or at the top of the heap is low down or high up in society or an organization.

If someone collapses in a heap, they fall heavily and untidily and do not move.