Alright kiddo, so imagine the Earth is like a big round ball. Now, we want to measure where things are on this ball so we have imaginary lines all over it called "longitude" and "latitude". Longitude are the lines that go up and down from the North Pole to the South Pole.
The line we're talking about today is called the 104th meridian west. This particular line starts at the North Pole, goes straight down through Canada and the United States, and ends up at the South Pole.
The 104th meridian west is pretty important because it helps us know where things are in relation to other things. For example, if you wanted to know where the Great Plains are in the US, you could use the 104th meridian as a clue, because that's where they are located.
Overall, the 104th meridian west is just one of many lines that helps us understand where things are on a map of the Earth.