I want to understand the prefix or the notations in routing table?

Hello Girish Pant,

i will explain the above routing table step by step o clarify your doubts,

1. 

10.0.0.0/32 is subnetted, 4 subnets

O 10.1.1.1/32 [110/2] via 192.168.0.1, 00:00:40, GigabitEthernet0/0

O 10.2.1.1/32 [110/2] via 192.168.0.1, 00:00:40, GigabitEthernet0/0

O 10.3.1.1/32 [110/2] via 192.168.0.1, 00:00:40, GigabitEthernet0/0

O 10.4.1.1/32 [110/2] via 192.168.0.1, 00:00:40, GigabitEthernet0/0

In the above the routing table information the router is learning above the network 10.0.0.0/32 via OSPF that it why it shows O in the beginning of the route information and the information it is getting is via Interface GigabitEthernet0/0.

Coming to your question it shows  10.0.0.0/32 because you must be having loopbacks configured on the other router, you can set a loopback with a /24 address and to see on the other end of your OSPF domain how the same loopback is advertised. You will find that, your /24 subnet will be advertised as a /32 in OSPF.

In order to see the exact same network information with the correct subnet mask you must specify the loopbacks in OSPF  as POINT YO POINT Networks.

However, 

2. 

192.168.0.0/24 is variably subnetted, 4 subnets, 2 masks

C 192.168.0.0/30 is directly connected, GigabitEthernet0/0

L 192.168.0.2/32 is directly connected, GigabitEthernet0/0

C 192.168.0.4/30 is directly connected, GigabitEthernet0/1

L 192.168.0.5/32 is directly connected, GigabitEthernet0/1

In the above route information the network 192.168.0.0 is of class B if i talk above classfull network but in this case it is subnetted with subnet mask 255.255.255.252 hence it shows prefix as /30 as connected network to various interfaces.

I hope the above information given by me solves most of your queries.

Feel free to ask if you have any other question.

CHEERS THANKS !! :)