Newly harvested rice—the season's fresh rice crop (as opposed to old rice).
新米の炊きたては香りが良い。
Freshly cooked new rice smells great.
今年の新米は粒が大きくて美味しい。
This year's new rice has large grains and is delicious.
A novice or beginner—someone inexperienced (used figuratively as 'a new hand' or 'rookie').
彼はまだ新米の記者だから取材に慣れていない。
He's still a novice reporter, so he's not used to reporting yet.
新米のうちは失敗して学ぶことも多い。
When you're a beginner you learn a lot through making mistakes.
新米の農家は収穫時期を慎重に判断した。
The novice farmer carefully judged the harvest time.