how can i determine if a person is in the left or right side of the player in the X axis?

I’m making a project in Roblox Studio which is a fighting type game. The thing is, it’s 2D. So if a person is on the right side of the player, the player should look right else if the person is on the left side of the player, the player should look left. This must happen to every player in the game. What are the things that I must know on doing this? Like CFrames, Vector3, Lerp? I would appreciate it if some people could help me. Thanks again!