Make a speach bubble appear on an object when clicked.#?

An option you have is to use ClickDetectors and the Chat service.

To detect a player clicking the part, you should use a ClickDetector.

As for making the part talk to you, Chat service can make a speech bubble appear.

local ClickDetector = script.Parent -- Location of the ClickDetector
local part = ClickDetector.Parent -- Location of the part
local chat Service = game:GetService("Chat")

clickDetector.MouseClick:Connect(function(player)
    chatService:Chat(part, "Message", "Color") -- Replace "Color" with an actual color such as "Red"
end)

If you want the player to have dialog options to communicate with the part, you should use Dialog.