SKAP 5V 7A 5-Pin Sugar Cube Relay Switch (PCB Mount) is an electromechanically operated switch. The term 5V 10A means, with a compatible voltage of 5V it can pass max 7A current. And for the max power rating as it is written on the product 30VDC, with 30VDC it can pass max current 7A. It is a single pole double throw (SPDT) relay, with having a common terminal that connects to either of two others, including two for the coil, such a relay has five terminals.
Relays are generally used when it is necessary to control a circuit by low-power signal, or where several circuits must be controlled by one signal. It is a very must-have component for any electronic project where you need to control an AC device with a DC signal.