Single sided PCB is referred to a circuit PCB with one layer for conductance. This is generally most basic type of PCB and has components on one side and connecting conductor on the other side. Because there is only a conductor pattern on one side, this type of PCB is called‘single-sided’ or ‘single–layer’.
This type of circuit board is suitable for simple circuits only. Because there is only one side, no wires can cross and they have to be routed around each other. This type of PCB is most famous in through hole PCB though surface mount chips with very basic functionality can also use the same. Single layer PCB (www.treepcb.com)has further limitation as it doesn’t involve complex designs or complex routing and limited to basic wirings and connections. This is famous amongst hobbyist students or can be considered as first part in first step inprinted circuit board manufacturing learning process. They usually have soldering holes or soldering pads, but they do not have vias connecting two layers. There is a complexity in single sided PCB as they do not support cross-over and we have to use jumper connection to connect wires over the surface. Hence, sometimes it requires more effort to design single sided PCB than double sided.
The best advantage of single sided PCB is low manufacturing and assembly cost. This is also good for hobbyist as it can be manufactured in home using basic chemicals. No separate lab or factory works are required. Single-sided PCBs made in volume costs less than half of what double-sided boards cost. One can use single-sided PCB for that if you are making it by hands, that is drawing the circuit on copper board and using FECL3 and stuff. It is difficult to apply similar techniques to make a two-sided PCB.

single layer pcb