All children are blessed with an immense aptitude to learn things rapidly. Repetition is another mantra as they tend to replace their learning with something that is fresher. Linking and connecting is also a concept which is almost like an instinct in them. They may hear a word, try to connect it with a subject and actually surprise us by expressing it in some other matter.
Pre schools have a wonderful way to instill rhymes and songs in a sing song fashion. Actions and mimicking is loved by them. While speaking the parent or caregiver must ensure eye contact and also speak the sound clearly. When in doubt one must always refer to the right pronunciation. Introduce one new word each day. It is studied that kids grasp words randomly but to ensure the right diction, reading is a wonderful medium.
As they learn to communicate verbally, they use less animated movements with their hands. Their facial expressions also convey much when they are not able to communicate via a word. Let them feel free to speak incorrect language. But ensure to correct the sentence. It is important to not interrupt them and let them take their time to frame a sentence.
If multi languages are spoken at home, then children have a natural ability to link things. Initially they may jumble up the languages with words but all in all the communication seems perfect. As they progress in school where the communication is in English, they gather a style and speak coherently. Vocabulary has to be encouraged by reading, phonics and also making it habitual to use new words. Gifting the child with books is the best reward to improve their word building skills.