The tags indicate the total value of each column of stamps, progressivelyaccumulatively across the page. I'd imagine these assisted the postal clerk with accounting/counting:

 
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Tony, from the images of those stamps, it appears that the stamps are mounted in what are known as "tubular mounts". These come in a few different brand names, "Crystal Mounts" being probably the more commonly known.

Through time, it has become known that these tubular mounts tend to retain humidity, and cause damage to stamps. It would be a good idea to carefully remove the stamps from these mounts. Store the stamps in a stock book for safekeeping until you decide what you want to do with them.

 
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There have been many such questions like that answered here.

This is one link:

https://stamporama.com/discboard/disc_main.php?action=20&id=5645#35328

In the Discussion Board, there is a search option. In the blue bar at the top of the page, click on "Search". A box opens. Change the selection to "Key Word", and type in whatever you are looking for, such as "stamp mount". You will see the threads that have been written that have a mention of what you are searching for.

I am not trying to dissuade you from asking questions. I'm just trying to show you that Stamporama has been around for a long time, and there are many discussions on all aspects of the hobby that may prove to be very helpful. The site has many tools and information available that are just a click or so away.

 
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