Answer:
They talk like normal coz they are
6-12 months
Typically, your baby will listen and look with a great deal of interest to what's going on around them, will start to babble ("gaga, bababa, mmmm") using strings of different sounds, and will be understanding simple words in context ("Where'sMummy?" "Biscuit's all gone").
What can you do?
Talking to your baby through the day, telling them what you're doing, and singing songs will all help your child's language skills. Get down to their level and make eye contact with them as you talk to them, and copy the sounds they make. Use simple actions and gestures as you talk too, like miming drinking from a cup as you say "drink", or waving as you say "bye-bye" - this will really help your child's understanding and vocabulary development.
12-24 months
At this age, your child will be starting to develop first words, typically single words at around 1 year ("Daddy", "doggy"), progressing to putting two words together at around 2 years of age ("Mummy gone"). The words might not be very clear though, and your child will be using gestures, pointing and reaching, along with different sounds, to get their message across.
What can you do?
When your child points to an object, tell them what it is. Be prepared to do this many times - repetition is how children learn! Play lots of action games and songs (libraries have plenty of books and CDs full of these), and remember to talk to your child as much as possible!
2-3 years
At this age your child will typically be understanding more, and have a larger vocabulary (using up to 300 words).
They'll be asking lots of questions too! Their speech sounds may be well-developed, but it's likely they'll be having some difficulties with trickier sounds like "sh, ch, j, th, r" and others.
What can you do?
Add language: If your child uses a sentence like "big doggy", you can help their language by adding a little to what they've said: "Yes, that's a big, brown doggy. Woof woof!" If your child has difficulty with speech sounds, so that some words are unclear, don't correct them or make them say it again: just repeat what they've said using the right sounds, and this'll help them to develop those sounds themselves.
3-5 years
Your child now has a lot to say! They'll be asking loads of questions, doing lots of imaginative pretend play, and learning to interact with their peers. They are starting to use much longer sentences too, although they'll still make grammatical mistakes ("I breaked the cup") and may have difficulties with those trickier sounds ("th, ch", etc).
What can you do?
Give your child plenty of time to talk! Try and make a special time at the end of each day to chat about what your child did during the day, remembering not to fire too many questions at them! Games which encourage turn-taking and attention skills (like simple board or card games) are great for this age-group.
5-12 years
This is a long period in which your child's language continues to develop. By 6 years of age, most of the speech sounds will be in place, and your child will be able to understand more complicated instructions. As they get older, their vocabulary will continue to grow, and they'll learn to use their language in different social situations, and for reading, writing and spelling. They'll understand more abstract concepts which are outside the "here and now", more complicated humour (like sarcasm), and start to use these themselves.