。
Practice makes perfect.
Literal
Practice [subject-が] perfect-ly [object-を] makes.
A rendering of 'practice makes perfect' using the native Japanese adverb 完ぺき ('perfectly, flawlessly,' usually written 完璧) + する ('to make'). The synonym 完成 ('completion') would shift the nuance toward reaching a finished state; 完璧 here emphasizes reaching a flawless state.