> Does that mean I will be able to open a terminal an type: WireGuard and from then on my connection to the internet will be secure
It's more like how iptables/nftables is part of the kernel. You need a recent kernel along with user space tooling. But it will become part of virtually every Linux distribution.
As for "my connection to the internet will be secure" - that's possible, but the main use case right now is "my connection to my vpn/server will be secure".
Additional configuration is required to route all traffic through the wireguard tunnel, and make sure all other traffic is dropped - and to make sure all traffic is dropped, rather than sent in plaintext when the tunnel goes down (a "kill switch").
I'm sure we'll see many tools and scripts that will help automate such setups.
But if you just want a udp routed VPN - you might want to look at zerotier or tinc.