What does the dB level in Song Info-File really mean? Is it adjustable?

I am using iTunes Version 12.13.7.1.

I record music using Audacity, version 3.7.3.

I save the Audacity file using the .wav (Microsoft) format.

I add a music file to iTunes using the .wav file.

Then in iTunes, I convert the file to ACC version.

I highlight the ACC version (right click) and select Song Info

In the Song Info window, select File

In the File window is listed all the file parameters.

One of the parameters in Volume.

What does this dB Volume indicate?

Input level at download? Play level?

Is it an 'average' dB level?

Is it adjustable? how?

iTunes for Windows v12.13.7