Language can be broken down into what a child understands and what a child can express.

Receptive language is known as the language someone can understand.  A child usually can understand more than they can express.  For example, in school a multiple choice test might be easier because you did not have to recall the exact word.  But a fill-in-the-blank test was harder because you had to pull the word out of your memory.  Fill-in-the-blank tests require stronger expressive language skills.

Expressive language is known as the language you can speak, write, or convey to someone.  This is not always verbal.  A lot can be spoken with only body language.  Children can use sign language, pointing, pushing and pulling to get their needs conveyed to another person.

Augmentative communication is when a child uses means to communicate other than speech.  This can be sign language, a communication board, or an electronic device that speaks for the child.

Pragmatic language refers to the social language skills children use in their daily time with others. This includes what is said, how it is said, the body language and whether it is appropriate to the specific situation. Pragmatic skills are vital for communicating personal thoughts, ideas and feelings.

Executive functioning refers to a set of higher level mental skills that help you get things done.  This can be things like working memory and processing of language.  These skills are vital the older children become.