"Canvas" can both mean a noun that refers to a type of rough, durable cloth or fabric commonly used in tents and outdoor coverings such as awnings, and a verb that means searching or covering a given area, usually in the context of personal outreach for a given goal or mission. The play on words here is that the manager of a business selling tents and awnings, commonly made of canvas, is telling his employees to help promote the business by *canvassing* the area to that end.
In his latest promotional campaign , the manager of City Tent and Awning told his crew to canvas the entire area .