My friend just told me that her 7 month old said 'mama'. My baby is almost a year old and hasn't even tried to say it. :( At what age do babies usually start speaking?

Different baby develops at different pace. My daugther speaks first word at 1 year old while my son speaks first word at 8 months old and in sentences at 1 year old. If your child has not started to speak at 3 years old, then you have to seek speech therapist's help.