1young; youthful — having a small age or appearing/feeling full of youth.
彼はまだ若いから失敗を恐れずに挑戦している。
He's still young, so he challenges things without fear of failure.
若い社員が新しいアイデアを提案した。
A young employee proposed a new idea.
若い頃の経験は大きな財産になる。
Experiences from one's youth become a great asset.
2immature; green — lacking experience or maturity (similar to 'green').
若い判断で無理をすると後で困ることになる。
If you make decisions with immature judgment, you'll get into trouble later.
若い発言に見えるが、経験不足が原因だ。
It looks like an immature remark, but it's due to lack of experience.
3Used of numbers/order to mean low or early (e.g., a low jersey number, an early ticket number) — a specific usage restricted to numerical rank.
彼の背番号は若いから、ベテラン選手だとわかる。
His jersey number is low, so you can tell he's a veteran player.
整理券の番号が若い人から順番に呼ばれます。
People with lower-numbered tickets are called in order first.