The Royal Navy is like a big group of people who work together to keep England safe, but they do it by sailing boats in the water instead of just walking around on land like regular people. They've been doing this for a really long time, starting way back in the 16th century when England was still ruled by a queen named Elizabeth I.
In those days, there were lots of other countries around the world who were also using boats to travel and trade, but some of them were not very nice to England, and so the queen decided that she needed to build up her own navy to protect her people. She started with just a few boats, but over time she added more and more, until the navy became a really big and powerful force.
The navy's job was to go out and stop other countries from attacking England, but they also did lots of other things, like exploring new parts of the world and helping to set up colonies in far-off places like America and Australia. They fought in lots of big wars, including the Battle of Trafalgar in 1805, which was one of the most important naval battles ever fought.
Even though the navy is not as important for protecting England today as it was in the past, it still plays an important role in keeping the country safe. The boats and equipment they use are much more advanced now, but they still have the same goal - to make sure that England stays free and independent.