Well from what I can see it looks like a tool, I think you can get this message by getting ChildAdded from the character and checking if the child is a tool. I added all the necessary explanations below.
local player = game.Players.LocalPlayer
local character = player.Character or player.CharacterAdded:Wait() --//This gets the character
character.ChildAdded:Connect(function(child) --//This is fired whenever an instance is added into the character
if not child:IsA("Tool") then return end --//This checks if the instance is a tool if it is not stops the rest of the code from running
local clone = player.PlayerGui.NewItems.Frame.Frame:Clone()
print(child.Name.." added!")
clone.Name = child.Name
clone.Parent = player.PlayerGui.NewItems.Frame
clone.TextLabel.Text = "+"..child.Name
clone.Visible = true
end)