why to use this keyword in c++ code example

Example: this in c++

#include <iostream>
class Entity
{
public:
	int x, y;
	Entity(int x, int y)
	{
		Entity*const e = this;// is a ptr to the the new instance of class 
		//inside non const method this == Entity*const
		//e->x = 5;
		//e->y =6;
		this->x = x;
		this->y = x;
	}
	int GetX()const
	{
		const Entity* e = this;//inside const function this is = const Entity*
	}
};

int main()

{
	Entity e1(1,2);
}