The 1930 Hours of Work Convention was a special agreement between countries to make sure that people who work in offices and other places where they do business, didn't have to work for too long each day or each week.
It said that the longest amount of time someone could work each day was eight hours, and the longest amount of time they could work each week was 48 hours.
The idea was to make sure that people weren't working so hard that it made them sick or tired all the time. The Convention was created by different countries that agreed to follow these rules and to make sure that all the workers in their countries were protected.
Nowadays, many countries have their own laws and rules that follow these same ideas, so people can work hard but still have a good balance between work and rest.