Not printing "A" when Player1 says "kill" or "Kill". Thanks for helping!
game.Players.PlayerAdded:connect (function(player) if player.Name == "Player1" then player.Chatted:connect (function(msg) if msg:lower() == "Kill" then print"A" end end) end end)
msg:lower()
converts all the characters to lower case, but you are comparing it to a string with an uppercase letter (the 'K' at the beginning). Therefore, the condition will never return true.
if msg:lower() == "kill" then print("A") end