Both left right and flashers do not work

My dad, retired 78 year old old mechanic can’t remember the name of the main thing that makes flashers work. He thinks it may be called the flasher module, he needs to order the part so he can install it. He knows it goes under the dash he tells me “ your just a girl” and “ have no idea how these things work “ Seriously I am not mechanically inclined. Help!
Just a girl.