The remaining two stages of analysis, semantics and pragmatics, are concerned with getting at the meaning of a sentence. In the first stage (semantics) a partial representation of the meaning is obtained based on the possible syntactic structure(s) of the sentence, and on the meanings of the words in that sentence. In the second stage, the meaning is elaborated based on contextual and world knowledge. To illustrate the difference between these stages, consider the sentence:
From knowledge of the meaning of the words and the structure of the sentence we can work out that someone (who is male) asked for someone who is a boss. But we can't say who these people are and why the first guy wanted the second. If we know something about the context (including the last few sentences spoken/written) we may be able to work these things out. Maybe the last sentence was ``Fred had just been sacked.'', and we know from our general knowledge that bosses generally sack people and if people want to speak to people who sack them it is generally to complain about it. We could then really start to get at the meaning of the sentence - Fred wants to complain to his boss about getting sacked.
Anyway, this second stage of getting at the real contextual meaning is referred to as pragmatics. The first stage - based on the meanings of the words and the structure of the sentence - is semantics and is what we'll discuss a bit more next.