Have you ever played with stacking blocks on top of each other? Parabolic cylindrical coordinates are kind of like stacking blocks on top of each other, but they are used to describe a point in space instead of making a tower.
Imagine you are standing in an empty field and you want to describe your location to someone else. You could say, "I am 10 feet north and 5 feet east of the big oak tree." That's called using Cartesian coordinates, which are like giving someone directions on a map. But sometimes, it's easier to describe a point using other types of coordinates, like parabolic cylindrical coordinates.
Instead of saying "north" and "east," parabolic cylindrical coordinates use two new terms: "rho" and "phi." Imagine taking the flat end of a toilet paper roll and looking at it straight on. If you draw a point in the center of the roll and draw a line out from the center, that line is the "rho" value. If you draw a line going around the roll from left to right, that's the "phi" value. So if you were standing in the field again, you could describe your location as being at a certain rho value and phi value.
But that's not all! Parabolic cylindrical coordinates also include a third value, "z," which is just like the north/south measurement in Cartesian coordinates. The rho, phi, and z values all work together to describe a point in space. Just like stacking blocks on top of each other, you can stack these coordinates on top of each other to pinpoint a specific spot.
So if you were at a specific rho, phi, and z in space, you could say something like "I am at rho=3, phi=45 degrees, z=7 feet." It's just like giving someone your GPS coordinates, but using a different system of measurement.