Standard peaking filter Node, frequencies inside a specific frequency range get a boost or an attenuation, and frequencies outside it are unchanged.
In other words, this Node can be used to increase or decrease the gain (or volume) only for a specific range of frequencies (e.g. to lower the volume around 1 kHz).
Audio and Control lines (visualized with blue and purple, respectively) are both analogous to an analog signal. They can be used interchangeably, and, for example, an Audio output (blue) can be connected to a Control input (purple), or vice-versa.
This Node and has exactly 2 samples of latency (equals ~0.0045 milliseconds at 44.1 kHz).