A Playblast, is a viewport render from the active camera, used commonly for previewing Animation, Staging and placement and the population of elements in a scene.

It is a term common to Maya users.

This is not a final render, and elements like NURB curves are also rendered.

You could say a Playblast is a video capture of the viewport.

Below is an example of a Playblast

https://player.vimeo.com/video/258455980

To create a Playblast in Blender, you can follow [this guide](/02/viewport-render-in-blender/).