Next Hop Routes are used to communicate with networks that the Ecessa device is not directly connected to. As an example consider the following diagram. The Ecessa's LAN is configured as 192.168.1.57/24 and the firewall's external interface is 192.168.1.58/24. Behind the firewall are two internal networks; 192.168.0.0/24 and 192.168.100.0/24.
In this example the Ecessa device is not aware of the two internal networks and does not know how to reach them. If direct communication with the internal 192.168.100.0/24 network was needed a Next Hop Route would tell the Ecessa device how to reach that network. In this example the traffic destined for the 192.168.100.0/24 network must be sent to the firewall's external address of 192.168.1.58 which is something the Ecessa device can reach. The Next Hop Route to accomplish this is in the following diagram.
The Source Network being 0.0.0.0/0 means that the traffic can originate from anywhere. The Destination Network is the traffic that will be sent to the Next Hop IP. The Next Hop IP is an address within a LAN or WAN configured on the Ecessa device that is able to reach the Destination Network.