How do I make a textlabel have a players name. Please help?!

Try this in a server script inside the button you're tryna click:

local players = game:GetService("Players") --Gets players
local ReplicatedStorage = game:GetService("ReplicatedStorage") --Gets replicatedstorage

players.PlayerAdded:Connect(function(p) --finds player object when player joins

    local pizza = ReplicatedStorage:WaitForChild("Pizza") --finds pizza
    local clonedPizza = pizza:Clone() --clones pizza
    local backpack = p.Backpack --backpack

    script.Parent.MouseButton1Down:Connect(function() --when button clicked

        clonedPizza.Parent = backpack --clone pizza to backpack

    end)

end)

If that won't work I can at least tell you what's wrong with your script:

What's wrong with your script?

local Player =     game.Workspace.Part.SurfaceGui.TextLabel.Text --I am assuming that you wanted to get a player object here, since you had a localscript you could have said game.Players.LocalPlayer
local PlayerGUI = game.Players.LocalPlayer.PlayerGui 

script.Parent.MouseButton1Down:connect(function() 
    game.ReplicatedStorage:WaitForChild("Pizza"):Clone().Parent = player.Backpack --You didn't define what player is, so you can't use it

You also didnt put and end) at the end

There, I'm probably wrong on most of these but whatever

game.Workspace.Part.SurfaceGui.TextLabel.Text isn't the player, it's just the text of a textbox which a string value. Assuming that this is a local script, beacuse you can only deal with GUIs and refer to the player from there, since all of these things are local, they belong to the computer that a certain player is using and not in the server that connects all players. To refer to the player in a local script you have to do game.Player.LocalPlayer

local player = game.Players.LocalPlayer
local PlayerGUI = game.Players.LocalPlayer.PlayerGui

script.Parent.MouseButton1Down:connect(function()
    game.ReplicatedStorage:WaitForChild("Pizza"):Clone().Parent = player.Backpack 
end)

Also you had some spelling mistakes

local Player =     game.Players.LocalPlayer
local PlayerGUI = game.Players.LocalPlayer.PlayerGui
local TextLabel = game.Workspace.Part.SurfaceGui.TextLabel.Text

    TextLabel = Players.Name
    script.Parent.MouseButton1Down:connect(function()
        game.ReplicatedStorage:WaitForChild("Pizza"):Clone().Parent = player.Backpack
end)

I figured it out, I just needed to add the TextLabel = Players.Name and it worked.