Wine & Proton
Wine
Wine which stands for "Wine Is Not an Emulator" is in fact a compatibility layer.
A compatibility layer is an interface which allows software written for one operating system such as Windows to run on another operating system such as Linux. It generally sits between the application and your system and allows your system to understand what the application is asking of your system. In other words its like a translator.
We can use Wine to run games that are not native to Linux, however if you own the game on steam then you will use Proton.
Proton
Proton builds on Wine and is for use with Steam, it is optimised for running games and includes DXVK, which translates DirectX 11 and 12 to Vulkan for improved performance.
There are multiple "flavours" of Proton, the official ones are installed through steam. Unofficial ones such as very good GE-Proton can be installed with applications such as ProtonUp-Qt. Custom versions of proton often come packaged with more libraries that Steam cant legally package.