The options under here are optional fields which you can use to Record things like Lawn Area, Bed Area, Snow Clearing Area, etc. These notes will appear on maintenance estimates and jobs that you create under this account, so they can be referenced when estimating, costing, or scheduling.
There are several predefined property detail fields for you to use, but if you would like to enter any custom data, you can make use of the Notes field, which works as a text box into which you may type whatever you like.