A proverb meaning that a skill or craft can help support you in life — having a useful ability can come in handy.
若いうちにプログラミングの勉強をしておくと安心だよ。芸は身を助けるからね。
It's good to learn programming while you're young — a skill can support you in life.
彼女は裁縫が得意で、困ったときに自分の技術で収入を得ている。まさに芸は身を助ける。
She's good at sewing and earns money with her skill when needed — exactly what 'a skill helps you'.