#include<iostream> here is iostream header mandetory ? and is there any meaning to these signs "<>" ?

Answer 1

iostream is a header, << statement/string
Example
#include <iostream> \\this is a heaer
using namespace std;
int main() this is in every C++ programm should start with main()
Than your functions and blocks like
{
cout << "Me:Hi, how are you\nThem:We good, thanks" << endl;
return 0;
}

Answer 2

Yes header is madatory, depends on functions you wanna use, otherwise you will get scope error
<> header signs