local remoteEvent = ReplicatedStorage:WaitForChild('RemoteEvent')
local player = game.Players.LocalPlayer
player.PlayerGui.Name.Frame.FirstName.Text = player.FName.Value
player.PlayerGui.Name.Frame.LastName.Text = player.LName.Value
It means whatever you were trying to index (get) failed and got nothing, maybe your syntax for getting the text label isn’t right or you can try to add :WaitForChild.