MacBook Pro Intermittent Shutdown. What does this kernel panic mean?

Panic Report, GPU Panic - Apple Community is one of perhaps thousands of reports from that era. It is generally considered fatal as those GPUs are no longer produced and the supply of used parts pulled from working Macs dried up long ago. The MacBookPro6,2 was specifically recalled for that problem, but that program also ended ages ago.

Scroll down to read OGELTHORPE's suggested workaround. Be advised I never tried it.

Macbook pro randomly restarting - Apple Community contains a link to the Apple Service Program that existed at the time. That page now 404s so if you want to know the specific details you will have to search the archives.

Your laptop has a bad GPU...that failure was common on the 15" & 17" models from about 2008 to 2011. It may be possible to force the laptop to use the integrated Intel GPU instead, but you will lose some functionality...not be able to use external displays, possibly sleep. If you search this forum, you will find some links to two different methods of forcing the laptop to use an Intel GPU instead. At the moment I don't time to go searching for those old links. The last time I posted that information was probably about five years ago.