Keyword research is the work of finding the exact words and phrases your customers type into search, so you build your pages around demand that already exists rather than guessing. It usually means checking which phrases people search, how often, and how much competition each one has.
For a small business, this is how you avoid building pages nobody is looking for. It surfaces the difference between a phrase you assume people use and one they actually type, and it often turns up specific, lower-competition searches, like a particular service in a particular town, that are far easier to be found for than a broad, crowded term. You end up writing for real questions instead of for a hunch.
Done honestly, it points to the pages worth building and the plain words to write them in. Each keyword you confirm becomes the backbone of a page aimed at one real search. It is groundwork, not a trick: writing pages around phrases customers genuinely search is a necessary condition for those pages to meet the people looking for them.