There are a number of settings that appear when you edit most layout types - they are described below
This is a simple text field to allow you to annotate a specific layout to make it easier to identify in your list of layouts.
Some options, when editing layouts, are considered non-basic so are hidden by default unless you enable advanced mode.
You can restrict layouts to only apply to articles from specific categories - this way you can create different output options for different types of content.
Note that "Applicable Categories" only appears on some layouts since it isn't relevant to some e.g. Category Blog, which is a type of 'wrapper' to display a series of separate articles (each of which could be formatted based on their category).
You can specify that only users of a particular access level would 'use' a specific layout in the same way that you can limit access to an article to certain user access levels.
If blocked access is enabled in the EasyLayouts options page you can specify that the access level is used to block access as opposed to allowing access. For example setting 'access' to 'special' and enabling the 'blocked access' level will create a layout that everyone who is not a 'special' user (i.e. Author, Editor, Manager, Administrator, Super User) will use. Using this option allows you to create different layouts for different groups of user.
If you have enabled Joomla versioning in the EasyLayouts options then you can add a 'Version Note' each time you make a change to a layout e.g. 'Stable version before experimenting' to make it easy to identify and restore from the versions archive.