Problem description:

I often saw this slogan on some walls when I was very young, but I still don't quite understand its meaning until now.

Analysis:

It should be "I will keep one night for everyone, and everyone will keep one year for me", that is, in order to maintain local law and order, everyone should patrol at night, each person only needs to patrol once a year, keep one night for others, and others patrol for you for one year. In fact, if there are few people, you might change the year to the month.