Wizards Of The Coast would like you to try out Magic: The Gathering Arena as soon as possible, and you're going to get your chance as a closed beta will be starting on December 4th. You can sign up for the beta here, but essentially this is to work out the kinks after they did initial testing with the alpha version of the game and they're looking for fan feedback as to how the beta plays out.
According to their own information, the closed beta will launch with Constructed matches and only Ixalan cards. So if you're not familiar with the latest sets, you might want to get some playing time in with someone who does. Also, anyone who signs up for the beta will be put under an NDA, so if that's not your cup of tea and you just can't help talking about it, you may not want to sign up right away.