Let’s go through the lines one by one:
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 1 0 0 eth0
This says that any packet with a destination of 192.168.1.0 through 192.168.1.255 will be sent out eth0 without using a gateway (unless a more-specific route overrides this one).
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.122.0 * 255.255.255.0 U 0 0 0 virbr0
This says that any packet with a destination of 192.168.122.0 through 192.168.122.255 will be sent out virbr0 without using a gateway. (Again, unless a more-specific route overrides this one.)
Destination Gateway Genmask Flags Metric Ref Use Iface
link-local * 255.255.0.0 U 1000 0 0 eth0
This says that any packet with a link-local address will be sent out interface eth0 with no gateway.
Destination Gateway Genmask Flags Metric Ref Use Iface
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
This says that any packet to a destination without another route will be sent out eth0, using 192.168.1.1 as a gateway.