Pads - Sampler

Press the Sampler button to set the Pads to Sampler mode.
Hold SHIFT down and then press the Sampler button to set the Pads to Velocity Sampler mode.

Sampler mode – Pioneer DDJ-RZ

Sampler pad page – VirtualDJ GUI

Each one of the 8 Pads triggers a sample from the selected Sampler Bank of VirtualDJ. If a bank has less than 9 samples, both sides of DDJ-RZ will control the same samples. If a bank has more than 8 samples, the left side of DDJ-RZ will control samples 1 to 8 and the right side samples 9 to 16. The PAD will be lit if a sample slot is loaded and will blink if triggered.
Press the Pads to trigger a sample. Depending on the selected trigger Pad mode, use SHIFT and the same Pads to stop the sample.
If Velocity Sampler is enabled the volume of each sample will be controlled by the velocity used to hit the pad.

Use the PARAMETER buttons to select the Sampler Bank (previous/next).
Hold SHIFT down and then the PARAMETER buttons to select the Trigger Pad mode (on/off, hold, stutter, unmute)

Read further details about Pads in the VirtualDJ 8 manual