I need help with making my NPC talk in chat, can somebody help?

I'm trying to make so when a button is clicked and it becomes invisible the NPC talks.

('a' is the name of the NPC)

while game.StarterGui.MainGui.PlayButton.Visible == true do
if game.StarterGui.MainGui.PlayButton.Visible == false then
game:GetService("Chat"):Chat(game.Workspace.a.Head, "EnterTextHere", Enum.ChatColor.White)
wait(2)
end
	end

I have no idea what I'm doing wrong, can somebody help?

(MainGui is the ScreenGui) (PlayButton is the text button)

It seems you are have been misinformed from your "experiment" or your brain has been melted from the coding part of the brain, Here, You did while game.StarterGui.MainGui.PlayButton.Visible == true do, this will only work if the playbutton is visible, when it was invisible it stopped and didnt run game.StarterGui.MainGui.PlayButton.Visible == false, So heres your fixed script!

local debounce = false

while true do
wait()
if game.StarterGui.MainGui.PlayButton.Visible == false and debounce == false then
debounce = true
game:GetService("Chat"):Chat(game.Workspace.a.Head, "EnterTextHere", Enum.ChatColor.White)
wait(2)
end
end