If you're concerned about your child's language development, the following skills are what to look out for:
-no babbling by the end of the first year
-not able to understand familiar words and phrases by age 12 months
-no pointing, gestures, or signs by age 12 months
-not able to follow simple one-step directions without accompanying gestures by age 15 months
-lack of eye contact
-no spoken language by age 2
If your child fits any of these, it's advisable to see a Speech Pathologist.
Generally 'late-talkers' are those children who have less than 50 words by 2 years. However, many words that a 2-year-old says are not clear and so many words they attempt may not have been considered a real word. It is normal for children under the age of 3 to have very unclear speech.
Check out this link for more info if you have concerns:
Speech and language development in infants and young children Caroline Bowen