Oval solder spots on universal pcb boards
There are many uses for these oval pads:


One can use them for connecting wires coming from another circuit.
As the pads are large, they can be used as a common pad.
Also, the pads can be used to solder thick wires. (e.g. power supply wires)
Helpful when a component needs to be mounted sideways.
They're handy for mounting headers along the plane of the board, either single-row, double-row, or box headers. Source for this point. 


Since, the PCB you have mentioned is used for prototyping circuits, its up to the user to decide how to use them and there can be many more scenarios in which they can be used.