expression, ichidan verb
improve one's skill; get better at something
Used when someone's ability noticeably improves, often through practice or experience. The 腕 here refers to one's skill or ability, not the physical arm.
最近、彼は料理の腕を上げた。
Lately, he has improved his cooking skills.
毎日練習すれば
If you practice every day, you'll improve your skills quickly.