Okay, so let's pretend you're a detective who lives in a really big neighborhood. There are lots of other detectives who live in different neighborhoods, but sometimes you need to talk to them to solve your cases. That's where the Secretary of State for Foreign and Commonwealth Affairs comes in.
The Secretary of State for Foreign and Commonwealth Affairs is kind of like the detective leader for talking to other countries. They live in a place called the United Kingdom and help the other detectives there talk to other countries when they need to solve problems together.
For example, if there's a problem in another country that might affect the UK, like a big flood or a war, the Secretary of State will talk to other countries' groups of detectives, called governments, to figure out how to help. They might talk to the leaders of those governments to ask for their help or to make sure that they're not doing anything that will make the problem worse.
The Secretary of State also helps other detectives in the UK travel to other countries safely. Sometimes, they might need permission from the other country's government to come in and help, or there might be rules about what they can and can't do while they're there. The Secretary of State helps make sure that everything goes smoothly and everyone is safe.
So, basically, the Secretary of State for Foreign and Commonwealth Affairs is a really important detective leader who helps the UK talk to other countries and solve problems together.