Speech says things, but it also does things
We need not get too far in the weeds. At a general level, it’s simply important to remember that every speech act operates on two levels. On one level, it communicates information or ideas. This is the semantic content of the speech, i.e., what the words mean.
On another level, talking is a social behavior. Every speech act is an act, meant not only to communicate something but to do something: reassure, acknowledge, nurture, enjoin, reject, dominate, encourage, or just fill awkward silence. We can think of this as the social function of a speech act. Unlike semantic content, social function cannot be understood in isolation, just by examining the words. Social function depends entirely on context, on tone and body language, on the interpersonal roles being played, on historical and environmental cues. It only makes sense relative to context.
All speech acts operate on both levels, but the ratio of social function to semantic content differs along a continuum. In some circumstances, speech acts take on an almost entirely communicative role: a surgeon narrating her surgery; a surveillance pilot describing troop movements; a university lecturer describing an episode of history.
But cases of purely communicative speech are more the exception than the rule, found in specialized professional or academic settings. As sociolinguists have come to appreciate, in day-to-day human interaction speech is a social, relational behavior. That’s why everyday patterns and rituals of speech are worthy of study; they reveal the social fabric.