The Canvas is a 27-inch display designed to sit on your desk under/in-front of your current display panel and offer you the sort of WYSIWYG functionality that a Wacom Cintiq or the Surface Studio offers you. It even comes with its own Surface Dial-esq puck which does some similar things to what the Surface Dial allows you to do (change colors, rotate the view, etc).
Another interesting aspect to the Canvas is that Dell specifically left a rather large bezel on the device to give artists and other creatives an easier time working around the edges of the display. On a traditional display the smaller bezels would make it hard to work around those outer edges because the users would have nothing to rest on.
Unfortunately, the Canvas looks as if it will be priced out of reach for many of us. Dells says the the new Canvas display will be available March 30th for a retail price of $2,000. Which is a bit steep if you ask me (for just a couple hundred more you could get a full Surface Studio system). However, if you already have a powerful desktop and want that Surface Studio capability this would be a way for you to get that without having to downgrade your specs buying a new Surface Studio.