Galatians 5:16 says walk by the Spirit, and you will not gratify the desires of what?

Answer: The flesh

"Walk by the Spirit, and you will not gratify the desires of the flesh," for the flesh and the Spirit are opposed to each other.

“So I say, walk by the Spirit, and you will not gratify the desires of the flesh.”— Galatians 5:16 (BSB)