Anyone know about iPods, macbooks and iTunes please?

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I have an old (perfect working order) iPod (maybe third generation) that I had paired to my MacBook and has all my music on (from ten years ago).
My MacBook died some years back, and I got a MacBook air, which I now use, but all the music ripped and downloaded from iTunes is on DD's iPod (a newish nano, the ones with Bluetooth, that they discontinued about 12 months ago).

Some of that music I would like to listen to ( well- I did pay for it , but she can keep the Clean Bandit stuff ).
If I connect my old iPod to the new MacBook/iTunes will it wipe all my old music? Or will it allow me to add new music to it? And how do I do that please?

TIA

I was in a similar situation a couple of years ago.
I just googled and followed the instructions.
It worked well, but I find iTunes very clunky in terms of sorting/arranging music, so, although I imported all the stuff on my iPod, it is stored on the Mac iTunes in a folder named PlainVanilla's iPod.

Thanks plainvanilla, I'll have a Google then