It's entry to mid level for AAA gaming meaning you won't be able to have all the graphical effects turned on.
There's a few things about the build that could be better, but if you are happy to play at 1080p 60hz, with medium settings, you will have a pretty good experience.
So here goes,
1. CPU - Ryzen 3200g, decent processor - maybe limited in some CPU intensive games like BF V. Something like a Ryzen 3600/2600 with more cores and threads is better for AAA gaming. Most games will use more cores/threads, and certainly so going forward.
2 GPU- is good for medium to high settings at 1080p. Mid range card.
3. Ram is only 1 x 8gb. This means you lose out on dual channel mode, which would bring you about 10-15% extra FPS (game dependant). Also the ram is slow. 2400mhz. Ryzen loves fast ram. Preferably about 3000mhz+. Faster ram would give you another 10-15% FPS over the 2400mhz.
4. The PSU isn't great, but it's not the worst, so it gets a pass, considering this is a budget gaming PC.
To answer your other part of the question - Thats the only redeeming thing IMO about the system. It IS upgradeable at least. You can swap in a new CPU/GPU and/or 2 x 8gb or 2 x 4gb matched kit for dual channel.