Form: Phonology, Morphology, Syntax
Content: Semantics
Use: Pragmatics
Second language acquisition (SLA): The process by which people learn a second language.
Phonology: The study of speech sounds and their functions in a language or languages.
Morphology: The study of structure and forms of words including derivation, inflection, and compounding.
Syntax: the pattern or structure of word order in sentences, clauses, and phrases, or the rules for determining how a language will be used to formulate a thought.
Semantics: The study of meaning in language, as the analysis of the meanings of words, phrases, sentences, discourse, and whole texts.