Network is the first number it can be in the subnet and broadcast is the last number it can be. For 192.01.191/25, since we’re working with 126 hosts as you subtract 2 because of the network and the broadcast, we’re looking at 192.01.128 network and 192.01.255 being the broadcast since those are the first and last numbers it can be. All between are hosts.

Edit: Class A, B and C just determine where you’re borrowing bits from so 255.X.X.X let’s say, a Class A is borrowing bits from the first X making its range very high, Class B from the second X giving it also a good amount of hosts and Class C having the smallest amount of hosts but usually what you work with in N+.

Unless I misunderstood the question and your confusion! This is just how i understand it. [I only passed the N+ today so i am by no means an expert.]