windows 10 - importing music

Can I import a song from youtube onto Audacity? If so, how?

It may be a copyright violation…

You should be able to [u]record it[/u] as it’s playing.

YouTube doesn’t want you downloading files but you can find tools for doing that. Once you have an audio/video file on your hard drive, Audacity can open the audio from it. (You’ll need the optional FFmpeg import/export library for most audio/video formats.)