Imagine you are playing a game of tag with your friends. Sometimes, you need to run to a "safe zone" where no one can tag you. This is kind of like what the Chinese police overseas service stations are for.
When people from China travel to other countries, they might need help from the police. Maybe they lost their passport, or got robbed, or got hurt. Instead of having to call the police in China and wait for help to arrive, they can go to one of these service stations for help.
It's like having a little piece of China in another country. The police officers there speak Chinese and can help with things like translation, filing reports, and keeping people safe. They also work with the local police to make sure everyone is following the rules and behaving properly.
But not everyone likes these service stations. Some people think it's unfair for China to have their own police stations in other countries, especially if they're doing things that the local police don't agree with. It's like playing a game of tag and having an adult step in and make up their own rules.