Language levels: PMSS — Phonology, Morphology, Syntax, Semantics (+ Pragmatics as a 5th level for social context). P=Phonology, M=Morphology, S=Syntax, S=Semantics.
PhonologySound system — phonemes distinguish meaning
MorphologyWord structure — morphemes, affixes
SyntaxSentence structure — grammar rules
SemanticsMeaning — word and sentence meaning
PragmaticsContext-dependent meaning use