In a routing table, the entry 0.0.0.0 is known as the default route. It is a special route that matches all IP addresses and is typically used as a catch-all route when there is no other more specific route available to forward traffic.
When a device needs to send a packet to a destination that is not covered by any other routes in its routing table, it will use the default route to send the packet to the next hop in the network. This next hop is typically the router or gateway that connects the device to other networks or to the Internet.
In summary, 0.0.0.0 is a special IP address that represents the default route in a routing table, which is used to forward packets to a next hop when no other more specific route exists for the destination.