1To be helpful or useful — to serve a purpose or provide some benefit.
このアプリは旅行の計画にとても役に立つ。
This app is very useful for planning trips.
先生のアドバイスが試験勉強に役に立った。
The teacher's advice was helpful for studying for the exam.
簡単な英会話フレーズは海外旅行で役に立つ。
Simple English conversation phrases come in handy when traveling abroad.
この道具は本当に役に立たない。
This tool really isn't useful at all.