Site properties are used to define certain aspects about your site.
Depending on the site type (solar, construction, mining), the site will change the site properties you have available. And these properties will improve the site analytics which will help you to make better and faster business decisions for that specific site.
Site properties can be edited at all times from the site overview page by clicking on the edit button highlighted in orange in the example below.
For learn more on solar site properties, please check out the following article.