A HugSQL developer works with the HugSQL library in the Clojure programming language, which provides a simple way to use SQL. They write SQL queries in SQL files, then use HugSQL functions to call these queries in their Clojure code. The developer is responsible for managing database interactions, transforming data, and ensuring efficient, secure database operations. They need to understand both SQL and Clojure, and be comfortable with functional programming concepts. Their work involves debugging, testing, and optimizing SQL queries, as well as integrating them into larger Clojure applications.