operator*() c++

Question

hello people
who can explain me this row in this code? why is int by reference?
int& operator*() { return *data; }

#include <iostream>
using namespace std;
class MyInt {
public:
explicit MyInt(int* p = nullptr) { data = p; }
~MyInt() { delete data; }
int& operator*() { return *data; }
private:
int* data;
};
int main()
{
int* p = new int(10);
MyInt myint = MyInt(p);
cout << *myint << endl;
return 0;
}

Answer 1

It's because you can do :
*myint = 3;
Here, thanks to reference, you can change the value of myint.