What opening is black playing

I'm 800 elo and I was playing as white, this is the first time I've seen this opening and I was wondering the best way to counter it. Luckily I won but it was a close game as it put me off a little bit

I'm 800 elo and I was playing as white, this is the first time I've seen this opening and I was wondering the best way to counter it. Luckily I won but it was a close game as it put me off a little bit