The durometer (duro) scale designates the hardness of and o-ring. A 70 duro ring will be softer than a 90 duro ring.
005 is a size designation.
I am still learning about these things, too. Do a few Google searches on o-rings. There are lots of charts and information about the wide range of o-rings available. For most of my airguns, I use Vito 70-90 duro o-rings that I purchase on eBay.