Have you ever heard of a grown-up's job called a press secretary? It's kind of like being the captain of a ship, but instead of steering the ship, they help the people who work for the leader talk to reporters and tell the people what's going on in the government.
Now, imagine that the leader lives in a special street called Downing Street. That leader needs someone to help them talk to reporters and share information with the people. That's where the Downing Street press secretary comes in! They work right next to the leader's house and help people share important information about what's happening in the government.
So basically, a Downing Street press secretary is a grown-up who helps the leader of a country share important news with the people in a special street called Downing Street. They're like the superhero sidekick of the leader, helping make sure everyone stays informed about what's happening in the government.