Solid State Relays are an efficient and simple way to switch on and off an AC circuit, by sending a 0-5V command signal.
This is a transistor-based switching technology, so there are no moving parts. Optocoupling keeps input and output circuits isolated from each other.
The maximum capacity of the switched circuit is up to 250V 2A. They can't handle as much load as the mechanical relays, but use less current to keep the circuit closed.
The module has both ribbon-cable connection, and screw-fastened connection options.
Connect your microcontroller's 5V+ and GND to the corresponding pins, and your data line to the channel to control. On the AC side, be careful: after unplugging the AC, cut the live or neutral wire, and have it pass through the switch side.