Although the BNB token is native to Binance, you can certainly buy BNB elsewhere. Bitpanda and Exodus can be good choices, or DEXs like Pancake Swap and Sushi Swap are also good alternatives. Do remember though, that to buy BNB on a DEX, you need to have a wallet that is compatible with the Binance Smart Chain.
For absolute crypto beginners, we usually recommend going with a platform like Binance because it’s designed to be so intuitive that anyone can get in on the game, any time. DEXes require a bit more setting up, but they are definitely worth checking out once you have the basics sorted and a feel for how crypto works.