When you're comparing a person to a computer system, wetware is the term for the human's brain. It's your wetware that controls your thoughts and feelings.
Soon after the invention of computers inspired the terms hardware and software, techies began referring to the human brain as wetware. If you think about a person's ability to make calculations and think logically, it makes sense that our brains are kind of like a computer's hardware — only squishier and wetter. More recently, wetware has also been used for the human minds behind the design of AI.