Encourage her to speak, applaud her words, praise her, pretend you do not understand sign language, show flash cards and encourage her to verbally identify, play
nursery rhymes and sing them with her, and may be let her be around her age children for a few hours everyday (say in a pre-nursery). If the child does not start speaking by the time she is around 3 years plus, consult his pediatrician regarding this. Take care!