script: script.Parent.Touched:Connect(function(hit) game.Players.LocalPlayer.PlayerGui.ShopGui.Frame.Visible = true end)
error: Workspace.Sell.Script:2: attempt to index nil with 'PlayerGui'
This is a script on the part, so there is no such thing as LocalPlayer. Only in LocalScripts.
Try this instead:
script.Parent.Touched:Connect(function(hit) local player = game.Players:GetPlayerFromCharacter(hit.Parent) player.PlayerGui.ShopGui.Frame.Visible = true end)
You cannot use LocalPlayer in a server script, but you can use getplayerfromcharacter(hit.parent).
script.Parent.Touched:Connect(function(hit) local player = game.Players:GetPlayerFromCharacter(hit.Parent) player.PlayerGui.ShopGui.Frame.Visible = true end)