We tend to think of language in two categories: oral language and literate language. Oral language is the language you speak or express. Literate language is the language of reading and writing.

Oral language is:
  • informal
  • conversational
  • here and now--contextualized
  • topic associated
  • occurs during social interaction, is content focused, and contains revisions and filler words
  • uses concrete vocabulary
  • basic sentence structure
Literate language is:
  • formal
  • spoken or written
  • there and then--decontextualized
  • topic centered
  • carefully planned and revised, contains content and form
  • uses abstract concepts and vocabulary
  • more complex sentence structure
Oral language supports reading comprehension and written language

If your child is young, you can help increase their expressive language by modeling language for them. Repeat back to them what they say, adding more descriptive language. 
  • If your child says, "block," you can expand and repeat the utterance back, by stating, "yes, that's a [color] block, a [size], [color] block." 
A child's first words often consist of nouns, and they later learn verbs, or action words. A child needs to have an expressive vocabulary (says these words on his/her own, not in imitation) of at least 50 words before they can combine two words to make a phrase. 

This is a great website with resources to increase your young child's expressive language skills:
https://teachmetotalk.com/2008/03/03/making-the-leap-from-words-to-phrases-tips-for-helping-your-toddler-learn-to-say-phrases/

*I do not own the rights to the linked website