Upon submitting to a journal, you will most likely have to supply keywords related to the manuscript being submitted. These words will become the main way people discover your published article when searching databases, so they should (1) be words that circulate in scholarship and (2) relate directly to your content or methods.
Keywords might relate to genre, movement, theory, population, subject of analysis, or region, for example.
southern gothic; boyhood; masculinity; queer theory
colonial rule; Panama; conservation; labor productivity
Look at the keywords connected to published articles similar to your manuscript or in the dictionaries of related databases.