A profession is a trade-oriented set of skills that characters can learn and gradually develop to collect, craft or improve items. Basically, WoW professions are 'jobs' that characters can acquire. Professions are learned and improved by a trainer for a small fee, or sometimes they can be advanced with special recipes. Professions can be learned regardless of a character's faction, race or class, although some racial traits give bonuses to a particular profession.
WoW Professions are limited to two per character, but one does not have to take any at all. You can unlearn a main profession to unlock a profession slot and learn something new, but you permanently lose all knowledge and experience gained in that profession. If you learn it again later, you will unfortunately have to start all over again.
ROGUE AUCTIONS offers you a quick overview of all recipes of all expansions for all professions, including Shadowlands. You can filter by reagent, crafted item, expansion or type.