Ardor is a scalable chain meant to be used for companies to develop their own services on top of it. While ARDR provides the "parent" chain for essential security reasons businesses can build "child" blockchains that run with their product in "software as a service" type applications for their customers.
Your Ardor investment also uses the proof of stake algorithm which makes it much more energy efficient and ecologically friendly than many other cryptocurrencies, something that is becoming a growing concern for much of the world due to Bitcoin's growing carbon footprint.
Interestingly, the child transactions from businesses using the ARDR chain can also be removed from the ledger after they are confirmed which helps to eliminate the massive problem of their platform becoming flooded with transactions that limit their efficiency as well. Essentially, ARDR makes it easy for any business to integrate blockchain technology into its own platform.
It's possible to buy Ardor on many top level exchanges, and you most likely won't have any trouble purchasing it from your accounts. BTC is the most popular trading pair for this coin so you'll most likely need to exchange your fiat or other cryptos for Bitcoin in order to trade for this coin.
It's best to store your tokens in your own wallet rather than leave them on an exchange. You have the option of using the official wallets which you can download from the official website or you can use the very popular Exodus multi-asset wallet if you prefer to store multiple coins in the same wallet. If you use the desktop wallet however you will be able to "forge" if you have over 1,000 coins which can earn you a small reward thanks to their Proof Of Stake algorithm.