The usual breakdown of language processing tasks
Signal understanding: translate signals (spoken speech or written characters) into some internal symbolic form. Produce phonemes or characters.
Phonology: group phonemes into morphemes
Morphology: group morphemes into words
Syntax: parse words into phrases, phrases into sentences
Semantics: connect words to objects and concepts in some internal representation language
Pragmatics: infer what is desired from what is said in a sentence
Discourse: constructing an argument, negotiating an agreement, (communication among agents)