What is Power BI?
Power BI is a dashboard reporting tool that enables users and customers to interact with data using interactive and custom visualizations, custom calculations, and queries.  You can build data models in Power BI, and you can run Power BI in direct query or import mode.  Direct Query queries the data directly from the system of record it connects to and import mode makes a copy of that data locally in Power BI.  Depending on the size of the dataset this can affect performance.