Even if you've never used a Mac, not knowing about homebrew is somewhat living-under-a-rock-ish.

Googling Homebrew comes up with

#1 - brew.sh, the homebrew homepage #2 - the homebrew github #3 - the homebrew wiki

It's really not that hard to figure this stuff out.

I should tell you to just google it, but you're also right. Lots of stuff that ends up on HN is actually really opaque about what the hell it actually is. See also, this item currently near the top: https://news.ycombinator.com/item?id=7669449

if you don't know what it is, it's probably not for you?