Don't understand rule from LANx to LANx address

[tinkerboy]

Hi, I just try to wrap my head around this setup I recreate from this NordVPN manual

This is the part where the rule is created: Next, click +Add, change Source to LAN net and Destination to LAN Address, don't change anything else, Save and Apply Changes.

This means I allow traffic from the LAN subnet to the interface IP of the LAN subnet?
Why would this not be allow anyway?
Here I found the explanation what LANx address stands for. The documentation hadn't been very helpful here.

Thanks for your expertise!