Why does heapSort run in n log N?

Question

Algorithms

I have a heap its height is log n. I want to sort it, n is the case not the number of vertices that need to be sorted?

Answer 1

N is the number of elements in the heap, when sorting, you need to get all the elements from the heap one by one, after each extraction, the heap must be rebuilt, this requires O (logN) operations.
The total is O(NlogN).