How do I make a sound play when a certain part is touched?

Assuming you have a part named Button in workspace, and a valid sound named Sound in workspace, this should work:

local debounce = false
game.Workspace.Button.Touched:connect(function(hit)
    if hit.Parent:FindFirstChild("Humanoid") and debounce == false then
        debounce = true
        game.Workspace.Sound:Play()
        wait(1.5)
        debounce = false
    end
end)

You need: A Sound in Workspace (Call it aSound) a script in the part.

debounce = true
script.Parent.Touched:connect(function () 
if debounce == true then
debounce = false
workspace.aSound:Play()
debounce = true
end
end)