WireGuard is an open-source VPN solution written in C by Jason Donenfeld and others, aiming to fix many of the problems that have plagued other modern server-to-server VPN offerings like IPSec/IKEv2, OpenVPN, or L2TP.
It can be seen as a replacement for OpenVPN although it does not have the versatility, possibilities and track record of OpenVPN.
However, it has two advantages over OpenVPN, it is much faster especially on lower-spec hardware such as Soho routers (my own R7800 goes from 85 Mb/s on OpenVPN to 270 Mb/s with WireGuard) and is easy to setup if you know how, the guides will help you with that.