This is probably the most easiest questien, but I am a derp and have no knowledge of lua or scripting (yet).
Do anyone know how to this? Example I hold a sword (or any tool in general) and I press T and from my head it says like "T" (or any word).
Simply detects when the 'T' key on the keyboard has been pressed. This should give you a start, try testing this by inserting a LocalScript into StarterGui.
local UIS = game:GetService("UserInputService") -- grabs userinputservice UIS.InputBegan:connect(function(input, _) -- recognizes input is being given if input.KeyCode == Enum.KeyCode.T then -- checks to see if the key pressed was the 'T' key print("T pressed") -- outputs to console (hit F9) end end)