In its simplest form, navigation is movement between two points as a function of three variables; direction, time, and distance. The tool pictured records and computes things. This is effectively a column in an abacus. There are 9 small beads in the bottom column, and 4 large beads in the top column. This marks, or counts 49 of something. At 50, the beads reset.
This device is made entirely of 550 chord, also called parachord. It makes no noise when you are walking or running, and is light (approx. 2 oz.). This, a compass with an inclinometer, and a mechanical watch, and you have the tools to navigate any map. Two or three of these, and you can do trig to solve for heights of mountains, rates of ascent/decent, etc.
The point is this little tool is part of what makes it possible to accurately travel between two points on a map.