There's a fan in it, and there are tips on the internet that they are not always quiet. My recommendation would be to invest in a real NAS, which costs a bit more, but you can do a lot more with it than with a WD NAS and there is also support and updates for years, so that would definitely be better and these fans in the Synology NAS, they are practically silent:

Synology DS220+ (2 x 1 TB, Seagate Ironwolf)