to improve one's skill; to get better at something through practice or experience
彼は毎日練習して、ギターの腕を上げた。
He practiced every day and improved his guitar skills.
新人だった彼女も半年でかなり腕を上げた。
She was a newcomer, but she improved a lot in six months.
料理教室に通って腕を上げたいと思っている。
I want to attend cooking classes to improve my skills.