Remote Events: How to get the name of the player the event was fired by?

The first argument on OnServerEvent is the player that fired it. Just use player.Name

LocalScript

RemoteEvent:FireServer("hello")

Script

RemoteEvent.OnServerEvent:Connect(function(player,word)
    print(player.Name)
    print(word) --> hello
end)

Just remember that the player parameter goes first, so although "hello" is the first argument in the LocalScript, it is the 2nd parameter in the script.