They love to hear differnet pitches and sounds. It' s important for parents to immitate the sounds babies make, and in turn the babies will imitate the parents sounds. Point out verbally everything you see. Even if the child is too young yet to understand, it enhances later understanding. Play and talk in front of a mirror, wave while saying bye-bye, put on puppet plays.
Children love to observe and are quick to understand and imitate.
Finally, it is important for parents to speak in short and simple sentences. Clarity is the key. Pictures and books are an opening to a child's world of creativity and imagination. The sooner a child is introduced to reading the stronger reading and creative skills will be. Initially, pictures need to be clear and familiar.