Okay kiddo, imagine the Earth is a big round ball. There are lines that go around the ball from the North Pole to the South Pole. These lines are called latitudes. The 55th parallel north is one of these latitudes. It is a line that is 55 degrees north of the equator, which is a pretend line that goes around the middle of the Earth.
So if you were standing on the Earth at the 55th parallel north, you would be in a place that is pretty far north. It would be colder and you would see things like snow and maybe even ice. This latitude goes through many countries including Canada, Russia, Norway, and Sweden. So there are lots of different places you can visit that are on the 55th parallel north.
But remember, this is just one of many latitudes on the Earth, and there are many things that make each one special.