Mesa 20.3.0 is the latest and greatest when it comes to Linux open source graphics, bringing with it new hardware support, performance improvements and more. Mesa drivers are what power the likes of Intel and AMD on Linux with the latest Vulkan and OpenGL support whereas NVIDIA have their own proprietary driver.
As always, with it being a brand new release if you're concerned about stability you might want to wait for the first point release with Mesa 20.3.1.
Lots new with this version like the 'V3DV' Vulkan driver for the Raspberry Pi now being available, new extension support, big improvements to the Zink driver (OpenGL implementation on top of Vulkan), new hardware support across both AMD and Intel for the latest chips and some upcoming stuff, the Panfrost driver for Mali GPUs was extended quite a lot too with out-of-the-box support for Arm's Mali Bifrost GPUs and much more.
You can see the release notes here, although they're quite technical and not great reading unless you really know what to look for.
Updates to Mesa depends on your Linux distribution, each is different. Need to learn more about Mesa drivers? See the official site.