The.com Elements are basically HTML elements, so their attributes are akin to HTML elements. Attributes are contextual, some Elements have lots and others may only have one or two.
Click on the top-right corner of an Element cell. This brings up the Element's Corner Menu, where there are buttons to Delete, Duplicate, Make Block, and Attributes. Click Attributes.
You will then have access to that Element's HTML attributes like id, class, href, src, autoplay, etc, depending on what type of Element it is.
These attributes are important to customizing your site and editing them is a core part of building on the web.
Click the grey "x" to exit this editing mode.