Tempo synchronization with a technical standard
The MIDI beat clock is used for synchronizing the bpm of the master deck to several time-based devices and programs.
If you change the tempo on the master deck all the connected programs/devices change to the same tempo. The beat clock makes use of a clock signal sent over MIDI. The MIDI signal exists of Clock events that are sent at a resolution of 24 steps per beat.
If you want to use the midi beat clock, you have to select a MIDI output in settings > MIDI. here, you can select your connected MIDI interface, or you can create a virtual MIDI device (virtual MIDI device is mac only).
After that, you have to connect the device that you want to use to receive the MIDI beat clock to the computer running ProDJLink with the MIDI beat clock output. Keep in mind that a beat clock only give an indication about the tempo, it does not indicate time.