Amplifiers increase the power of an audio signal to drive speakers. In car audio, the amp’s circuitry raises the head unit’s signal, then sends power speakers.
Monoblock amplifiers deliver power through a single channel. Often monoblock amplifiers drive subwoofers. “Strappable” monoblock amps can connect to combine power and drive the same speaker(s). Multi-channel amplifiers can send power through more than one channel.
Sending the wrong amount of power to speakers can cause damage to your system. To avoid damage speakers or the amp itself, learn how to correctly set up an amp.