"Eva" is short for "Entity Views Attachment;" it provides a Views display plugin that allows the output of a View to be attached to the content of any Drupal entity. The body of a node or comment, the profile of a user account, or the listing page for a Taxonomy term are all examples of entity content.
The placement of the view in the entity's content can be reordered on the "Field Display" administration page for that entity, like other fields added using the Field UI module.
In addition, the unique ID of the entity the view is attached to -- as well as any tokens generated from that entity -- can be passed in as arguments to the view. For example, you might make a View that displays posts with an 'Author ID' argument, then use Eva to attach the view to the User entity type. When a user profile is displayed, the User's ID will be passed in as the argument to the view magically.
That's right: magically.