RaycastHit2D can be used in an if statement to tell if the raycast hit anything, or if it hit nothing. This is because C# has the ability to do implied type conversions, and Unity has made it so RaycastHit2D can be converted to a bool. Pretty cool.

Example:

RaycastHit2D hit = Physics2D.Raycast(someStartPoint, someDirection);
 
if(hit) {
    Debug.Log("yaaay I hit something!");
}

This is also valid:

RaycastHit2D hit = Physics2D.Raycast(someStartPoint, someDirection);
 
bool rayHitSomthing = hit;