expression, noun
means of making a living; source of income; bread and butter
Idiomatic expression literally meaning 'seed of rice/meal', used to refer to one's livelihood or the source of one's income. Often carries a slightly colloquial or down-to-earth tone.
この仕事が私の飯の種だ。
This job is my bread and butter.
彼は翻訳を飯の種にしている。
He makes a living from translation.