The properties , agents, membership and invoices are created as custom post types. That means they are saved in the same way like a regular post. The table is called wp_posts. Any “meta details”(like n0 of rooms for a property) of these custom post type are saved in wp_postmeta.
If you planed to do customization of the theme , my suggestion is to use the wordpress api function for interrogating the database and not a direct sql query.