i noticed that when you hold an item it leaves the player backpack. Where does it go?
It goes under their Player module under Workspace. To get to it, do
game.Players.LocalPlayer.Character:FindFirstChild('insert tool name here')
Into the Player themselves
The tool goes into the Character which is in Workspace.
There are two manifestations of the person when they join a game. The player and the character. The player is the "digital" manifestation while the character is physical. So your hats, etc. It is in the Workspace.
The tool goes into the Character.