What wheels would fit my bike? I have a specialized pitch, unsure of the year, and my rear wheel was stolen. 

I have the front wheel which had the marking "ETRTO 584x25c" on it

What does this mean and what sizes of wheels would fit?
"ETRTO" stands for "European Tire and Rim Technical Organization" which means that's an industry standard sizing number.  You can just take your wheel to your local bike shop and get them to spec a replacement rear wheel of the same size.

If you want more detailed information, unfortunately Specialized (unlike some nicer brands) doesn't appear to have an easily accessible catalog of old products to search in. However there's a site called Bicycle Blue Book (presumably based on the Kelly Blue Book for cars) where you can search for previous year models.

You're probably not interested in the valuation, but the page for each bike includes product details, so you can make sure you're getting a comparable wheel.  For example, if you have a 2017 Sport 650B, the page will tell you it has "Shimano Center Lock" hubs and "[Specialized] Stout 650b, alloy, disc-only, double-wall, 25mm inner width" rims.

Note that older years are described as "650B" while from 2018 Specialized is using the term "27.5"; according to Sheldon Brown both of these are designations for (ETRTO) 584mm tires.