You stalk someone or something when you creep up on them without them knowing you are there. Animals like cats hunt their prey by stalking it and then pouncing on it.
A stalk is also another name for a plant's stem.
Talking is making words with your mouth and tongue. When babies are born they cannot talk, and they gradually learn how to talk in the first few years of their life.
A tuning fork is a specially shaped piece of metal that rings with a certain musical note when it is hit. Tuning forks are used to tune musical instruments to.