Never really used this kind of boards myself, I much prefer strip board. But since no one else answered they seem to be connectors where you can connect your circuitry for example +, -, and ground. Might want to get opinion from someone who actually has used board like that with connectors in place.
I too prefer strip board. I also have a little pcb with a 16 pin IC socket on it. Each pin of the socket comes out to a PCB pin at the edge of the board. They are ideal for doing a quick birds nest circuit and easy to make changes. Have had them for the best part of 40 years. They have been used for many many quick circuit developments both analogue and digital.