What is the meaning of the push_back function in vectors?

Push_back is to insert an element at the end of the vector,

The erase () function in the vector removes the element at the specified position from the specified container or an element within a range, and after deletion, the return value is also an iterator pointing to the next element of the last deleted element.

The problem is that the iterator becomes a wild pointer and needs to re-point the iterator pointer to begin or assign the returned iterator to the original iterator, or it will report a compilation error

iter = Vetcor.erase (ITER);

Or

Vectore.erase (ITER);

Iter=v1.begin;

What is the meaning of the push_back function in vectors?