Yes, GPU = "Graphics Processing Unit"...sorry, just easier to type than the longer names, but it is the graphics card
What determines GPU, though...well, that's a very long (and often hotly contested) discussion...I rely on two things, mostly:
- My own (350+ record) database of GPU benchmarks compiled over time
- The many, many online videos and reviews and comparisons, showing FPS of practically any card, usually as compared to practically any other card (or any other 3+ cards, often, all in the same video).
Mind you, what's important is rather than taking any one set of info as gospel, you're much better off looking at lots of different reports/comparisons. If you see one claim that card X will do (whatever), that's one thing...but if you see similar results from a multitude of sources, then it's probably fairly reliable.
Hopefully that helps