Excel is kind of a connection. To display Excel data in your app:
Note: Once you connect to your Excel table from PowerApps, PowerApps will create a new column called __PowerAppsId__, with a unique ID for each row of your Excel table.
Overview of the cloud-storage connection shows you how to add the connection, add an Excel table as a data source, and use the Excel data in your app.
For information about how to connect to other types of data, see the list of connections for PowerApps.