To be skilled or very capable at something; an idiom meaning one has good ability or technique.
彼は料理の腕が立つので、プロ並みに美味しい料理を作る。
He's skilled at cooking, so he makes restaurant-quality dishes.
あの大工は腕が立つから、細かい仕事も任せられる。
That carpenter is very skilled, so you can trust him with intricate work.
テニスの腕が立つ友達と練習すると上達が早い。
Practicing with a friend who's good at tennis helps you improve quickly.