JTBD describes a customer's want to make progress in their life.
Jobs to be Done (JTBD) is a theory of consumer behaviour. But often constraints stop them from making progress.
Other ways to describe JTBD:
If I had asked people what they wanted, they would have said faster horses — Henry Ford
When Coffee Meets Kale (book) — Alan Klement
Ok, so customers have a job. That much is clear! But it's a common misconception that the job is purely functional (e.g. grilling a burger). It's about making progress in one's life (e.g. hosting a birthday party).
JTBD is about a customer making progress in their lives. It's not about any one attribute of your product.