DLL files

Hi

In the “runtimes” of my monogame project there are 2 DLL files: SDL2.dll and soft_oal.dll
What are they for?

MonoGame uses SDL, OpenGL, OpenAL, etc to interface with some platforms (as opposed to something like DirectX, DirectInput, DirectSound, etc for a WindowsDX platform target).

More info: Platforms | MonoGame Documentation

So soft_oal.dll is OpenAL, correct?

Yes, specifically OpenAL-Soft in this case.