i dont drink alcohol.
edit: lol at people that cant stand a harmless joke, i dont even freaking know what root beer is and i doubt its even comercialized in my country, hate for uk tho can be world wide
It's like a sweetened, fizzy sassafras drink. Pretty good depending where you get it.
The USA has a weird thing where we use the words for alcoholic drinks to describe non-alcoholic ones. We also call spiced fruit drinks "cider" and actual cider "hard cider". Not sure why.
The guy that commercialised it was a teetotaller and wanted it to be called Root Tea, but because his target market were miners in Pennsylvania, he opted to call it Root Beer instead.
From my understanding, that title would be more accurate too, as it is produced from molasses with extract rather than grain mash, but my source is "skimmed Wikipedia" on both topics, so you should probably default to skepticism.
Either way, it apparently doesn't taste like beer, comes in both alcoholic and non-alcoholic* variants, usually doesn't contain caffeine and has a ton of flavours and variants from all over the world. If you care, you probably can find some.
*The process does involve fermentation, so I assume it will contain some ethanol still, even if it's below the threshold for the "non-alcoholic" label, in case that's an issue for you.