Translation:We should think about it before taking action.
That's one usage. See 2nd point here: https://www.frenchtoday.com/blog/how-to-use-the-pronoun-y-in-french
The context of the conversation should indicate who nous is. On can be used in generalizing statements, meaning "one," as in "One should not drive and talk on the phone" (On ne devrait pas conduire en parlant au téléphone). On is perfect for sweeping generalizations, but also as a casual substitute for nous. That is from Quora. Seems to me like think before acting is pretty general