Meshnet is their peer-to-peer secure networking solution, not their conventional VPN solution. It allowed you to have multiple devices in your account directly communicate with one another, set a device as gateways for routing network traffic of devices connected to Meshnet (basically making your own VPN server), sending files directly between devices, and likely more I'm not aware of.
It was essentially their Tailscale / ZeroTier offering, but in the opposite manner to Tailscale which added Mullvad integration to provide a more conventional VPN atop their mesh network.
They are removing Meshnet, and the primary capabilities of NordVPN will be their global set of traditional VPN servers. Some of the features like P2P file transmission can be replaced by e.g. NordLocker albeit without P2P if I understand it correctly. But mesh networking is gone in December.