These Fundamental Milestones
Your child should be learning words rapidly. He should also be beginning to combine two words into short phrases. His speech may consist of developmental errors in which he is simplifying words that are difficult to say by substituting easier sounds or omitting sounds all together.
2-3 years old
Your child should be starting to combine three to five words into sentences when talking. His vocabulary should be too big for you to count easily. He should be expressing novel thoughts and structuring them into statements that are more adult-like in nature.
3 years old
Your child should be easily understood by most listeners including strangers.
Note: Children who do not achieve all of the milestones in their age group before moving to the next need to be evaluated by a speech language pathologist.