It helps you better identify the information for which you are looking
Example:
What are the most effective methods of improving the quality of cross-cultural communication in the workplace?
Identify the main facets or key concepts of your research question
It helps you get to the heart of your topic, and start identifying possible search terms
Example:
communication / cross-cultural / workplace / improve
Brainstorm keywords, phrases, concepts, etc. that further describe those facets or key concepts
Because research databases often use different terminology than you might first consider,
it is helpful to think of alternate words so that you do not "hit a brick wall" as you begin the search process