Visualizations (known as visuals for short) display insights that have been discovered in the data. A Power BI report might have a single page with one visual or it might have pages full of visuals. It's important to make the distinction between report designers and report consumers. If you are the person building or modifying the report, then you are a designer. Designers have edit permissions to the report and its underlying dataset. In Power BI Desktop, this means you can open the dataset in Data view and create visuals in Report view.