A pure substance is an example of a homegenous mixture that is very evenly mixed. is that right?

A pure substance and a homogeneous mixture are two different things.

A pure substance is anything that is completely by itself. (An element, pretty much)

A homogeneous mixture is a mixture of 2+ compounds that you can not differentiate the separate substances in the product. Such as soda, it is all one color and one texture, but there are many compounds in it.