with quietness

"in a quiet, peaceful, and mild manner." Paul exhorts the meddlers to stop getting involved in other people's affairs.

eat their own bread

Bread here is a synecdoche for any kind of food. See how "bread" is translated in 2 Thessalonians 3:8. Alternate translation: "eat their own food" (See: rc://en/ta/man/jit/figs-synecdoche)