A Power BI dashboard is a single page, often called a canvas, that tells a story through visualizations. Because it's limited to one page, a well-designed dashboard contains only the highlights of that story.
The visualizations on a dashboard originate from reports and each report is based on a dataset. One way to think of a dashboard is as an entryway to the underlying reports and datasets. Selecting a visualization takes you to the report (and dataset) that it's based on.
Dashboards are a wonderful way to monitor your business and see all of your most important metrics at a glance. The visualizations on a dashboard can come from one underlying dataset or many, and from one underlying report or many. A dashboard combines on-premises and cloud data, providing a consolidated view regardless of where the data lives. A dashboard isn't just a pretty picture. It's highly interactive and the tiles update as the underlying data changes.