You can route audio into/out of a modular synth with this but the main selling point is being able to send CV or control voltage signals from your DAW to your m

You can route audio into/out of a modular synth with this but the main selling point is being able to send CV or control voltage signals from your DAW to your modular. CV is just DC electrical signal that represents some value you want to manipulate. Think of 0v representing the lowest note/frequency on the keyboard and 5v representing the highest, with all voltages in between representing intermediate values, or 0 representing a filter being set to the lowest frequency and 5 representing completely open, letting all sound through. Boutique analog equipment that can manipulate/sequence CV is usually pretty expensive, but with a module like this you can get similar/more functionality for less.