what is dynamic memory with very easy language ?

Answer 1

Dynamic memory is allocated on the fly during the execution and this allocation can persist between function calls. In C++, you use the keyword new to allocate memory dynamically, and delete to free it.

int *p;
p = new int(42);
cout << *p << endl;
delete p;

Answer 2

dynamic memory is the memory you can allocate or free on your own.