This is simply an extra few bits for KyroPaul's odometer.
The window bit acts as a gentle spring to stop the wheels over- rotating and they also provide a hole through which to view the number.
The cogs file is a plate of the main wheels already assembled, instead of being printed in three parts that you have to put together yourself.
The axels are just axels - print them diagonally across your plate for strength, push them through (you will have to drill out all the holes to make things spin easily) and then cut them to length when you're finished.
The numbers are created on a Dymo Letratag label printer large size font, vertical alignment with two spaces between each number and then just wrapped round the cogs - a perfect fit (hint: enter the numbers 0, 9, 8, 7 etc)
You'll need to download the box and other cogs from KyroPaul's thing - 90076.
Glue the windows/spring things in place with some acetone/filament scraps glue making sure they aren't holding the cogs too tight.