The matter feeds the black hole, it falls on it and emits intense radiation. This phenomenon is called accretion . If the black hole is rotating, it is able to accelerate the nearby gas, and to expel it out from the nucleus, as a couple of jets. The jets would be aligned with the rotation axis. For example, the radio lobes of radiogalaxies could be explained in such a way.
Jets are a much common phenomenon in active galactic nuclei.
After the idea of a central black hole was accepted, it was also proposed that the same mechanism could generate the great variety of the active galaxies. According to the so called unified model , if one changes the mass of the black hole, or the morphology of the host galaxy, or the viewing angle, then one obtains a radiogalaxy or a Seyfert one. M87 is a E1 elliptical galaxy in the Virgo constellation. It was identified as the strong radio source Virgo A, and it is also very bright in the X band. It is an active galaxy, probably hosting a central black hole.