computer networks – Total delay of packet switching

Suppose that x bit of message is transmitted over a k-hop path in a network.The circuit set up time is s seconds,the propagation delay is d seconds per hop.The packet size is p bits and data rate is b bps.At what time user will receive the message if Packet switching is used.

Over the packet-switched network, the total delay includes two
parts: the total propagation delay kd, and the transmission time at
each hop. For the transmission time, the x-bit user data is split into (x/p) packets. These packets are pipelined during the transmission.
It can be seen from the following illustration that the transmission
time part = x/b + (k-1)p/b. So, the total delay = kd + x/b + (k-1)p/b. I have found one solution (problem -2) but don’t understand pipeline concept .
I don’t understand k-hop paths means k-number of hops including source and destination or K-number of path? And don’t understand pipeline line concept.
Please see this .

If I don’t use pipeline concept what will be total delay.