Mac book pro

The model year of a MacBook Pro is available at Apple menu > About This Mac.

An Early 2008 through mid 2009 MacBook Pro can be upgraded to El Capitan 10.11.6 but no later version. See: How to get old versions of macOS - Apple Support

A mid 2010 through late 2011 MacBook Pro can be upgraded to High Sierra 10.13.6 but no later version. See: How to get old versions of macOS - Apple Support

A mid 2012 through early 2013 MacBook Pro can be upgraded to Catalina 10.15.7 but no later. See: How to get old versions of macOS - Apple Support

A late 2013 and mid 2014 can be upgraded to the latest  version of Big Sur macOS 11 but no later. See: How to get old versions of macOS - Apple Support

An early 2015 or later can be upgraded to the current version of Monterey macOS 12. See: How to upgrade to macOS Monterey - Apple Support

Yes it still gets updates as I have the mid 2012 model and I still receive updates for Safari as well as the Security Updates. I can't run the latest (newer) OS. macOS Catalina (10.15.7) is what I have installed and it works fine for me. You can upgrade the RAM (install more modules up to 16GB) as well as upgrading the internal hard drive to a much faster Soldi State Drive (SSD). With both hardware upgrades you will immediately see the benefit.

To follow up on Anthony's information, a 2012 Macbook Pro must be NON-Retina to have user upgradeable RAM. Easiest way to tell? The non-Retina 2012s have an optical drive. Both Retina and non-Retina Macbook Pros were made in 2012.

RAM on Retina Macbook Pros is soldered to and integral with the logic board, so cannot be upgraded once it leaves the assembly line. Storage is upgradeable on 2012 Retina Macbook Pros but will not be much faster if any.

My non-Retina Mid 2012 Macbook Pro 13" has been upgraded to 8GB RAM, but the massive speed increase came from replacing the glacially-slow factory mech hard drive with a 6G SATA solid-state drive. The computer went from being a slow pain to a fast joy to use. I am using it to type this and it still satisfies.

Old Greybeard's tip: If you replace the hard drive, replace the hard drive CABLE at the same time. That cable is about the only weak spot in an otherwise nearly bulletproof model. The cable is thin and its insulation thinner. Through normal use and transport the cable can chafe against sharp metal edges on the chassis. If the insulation fails you can get any number of oddball symptoms that will have you pulling you hair out.

Cables are available, cheap (under US$20) and easy to install when changing a drive.