Error in my script?

15 m = Instance.new("TextLabel", game.StarterGui.ScreenGui.TextLabel)
16 m.Size = UDim2.new(0, 500, 0, 50) --Make sure to use UDim2, NOT Vector3
17 m.Position = UDim2.new(.5, -500, .5, -340)
18 m.TextColor = (1+,+ 1, 1)  
19 m.Text = "Stuff" --Make sure this is a string
20 m.BorderSizePixel = (1.5)
21 m.BackgroundColor3 = Color3.new(1, 1, 1) --GUIs only accept Color3 values, which range from 0 to 1. To convert other colors to Color3, divide each number by 255. In this case, white is (255, 255, 255) and 255/255 = 1.
22 m.BackgroundTransparency = (1)

The numbers at the beginning of each line represent their lines in the full script, I put + around what's underlined in red.

The script analysis says;

Error: (18, 17) Expected ')' (to close '(' at column 15),got','

What have I done wrong and how do I fix it?

You have to use the Color3 scale to set the TextColor property, The Color3 scale takes 3 arguments.. each a number out of 255. Your values would make it white, just so you know.

Fix;

m.TextColor = Color3.new(1, 1, 1)