The PlayerRemoving event fires right before a Player is leaves the game. This event fires before Instance/ChildRemoved|ChildRemoved does on Players, and behaves somewhat similarly to Instance/DescendantRemoving. Since event fires before the actual removal of a Player, this event is useful to store player data using a GlobalDataStore.

This can be used alongside the Player/PlayerAdded event, which fires when a player joins the game. For instance, if you would like print a message every time a new player joins or leaves the game:

local Players = game:GetService("Players")

Players.PlayerAdded:Connect(function(player)
	print(player.Name + " joined the game!")
end)

Players.PlayerRemoving:Connect(function(player)
	print(player.Name + " left the game!")
end)

If you want to track when a player’s character is added or removed from the game, such as when a player respawns or dies, you can use the Player/CharacterAdded and Player/CharacterRemoving functions.