There is a simple and effective way to toggle between Report, Data and Model views in Power BI Desktop Application. You can use left hand side toolbar menu to achieve this quickly.
Default view is Report View. Power BI Desktop Application starts with this view. It is used for designing and viewing a report.
Second view is called Data View. In this view you can browse your underlying data in your data set. Select this view and change Fields on the right side to view sample data.
Third view is Modeling View. In this view you can do modeling tasks, design the data model of your report, see and define the relationships between entities and change other metadata related information.