If we want to analyse which part or section of a sentence makes language, communication and speech possible, we need to look at the following elements: Nouns, verbs, pronouns, determiners, adjectives, adverbs, prepositions and conjunctions.
These are the bare bones of the language and put together they become segments, known as phrases which in turn can create sentences.
All have different functions that are explained in further detail on the pages accessed by the links to the left.