Microsoft has struggled with the ability to provide easy, customizable forms for a number of years. Once a certain level of either complexity or customization was required the form either got scrapped or was handed over to IT to build. SharePoint and InfoPath were Microsoft's major solution to allow business users the ability to create their own forms without involving IT.
Canvas Apps allow any level user to design forms or applications in a similar manner to creating a PowerPoint slide. It has a drag & drop interface and the ability to connect to multiple data sources. Besides basic forms, it is possible to generate complete applications that have multiple screens that allow users to Browse, View Details, and Edit information.
The easiest way to start is to point to a SharePoint list. In the menu there is a new option called Integrate that allows you to connect to Power Platform tools. If you select Power Apps -> Customize forms.
A basic list will generate a basic form that allows customization. It adds in the Title field and allows the ability to upload items.