You can find simple description about WPL DB Tables here. Also you can download DB diagram from attachments. This KB is as is.
wp_wpl_properties: This table stores properties information.
wp_wpl_users: This table stores WPL users (Agents) information.
wp_wpl_dbst: This table stores list of WPL field which exist in the wp_wpl_properties (or wp_wpl_users) table. because the properties table schema is dynamic, we save the field information over here.
wp_wpl_items: This table is for several purposes, For example for saving image of the properties or saving rooms of properties etc.
wp_wpl_menus: WPL menus saved on this table. You can add new menus using this table.
wp_wpl_units: Contains list of Length, Area, Volume, Currency units. You can add new units using this table.
wp_wpl_dbcat: Categories of the WPL fields (wp_wpl_dbst table). For example, Basic Details, Gallery, Address Map etc. You can add new categories or manage current categories using this table if needed.
wp_wpl_addons: List of installed WPL addons.
wp_wpl_logs: Stores WPL logs (If any).
wp_wpl_settings: WPL uses advanced settings form generator. This table contains the settings list and their data.
wp_wpl_cronjobs: List of cronjobs for running in certain periods of time.
wp_wpl_property_types: Property Types save over here. Records with parent:0 are categories.
wp_wpl_listing_types: Listing Types save over here. Records with parent:0 are categories.
wp_wpl_activities: Activity is something like widget but just used by WPL, For example google map is an activity or image gallery etc.
wp_wpl_events: An API for running codes in a certain hook. For example after adding a property or finalizing a property etc.
wp_wpl_filters: An API for filtering WPL values. Its concept is like WordPress filter system.
wp_wpl_location1: Level 1 locations (Country).
wp_wpl_location2: Level 2 locations (State/Province).
wp_wpl_location3: Level 3 locations (County).
wp_wpl_location4: Level 4 locations (City).
wp_wpl_location5: Level 5 locations.
wp_wpl_location6: Level 6 locations.
wp_wpl_location7: Level 7 locations.
wp_wpl_dbst_types: Type of WPL fields. This type uses in wp_wpl_dbst table. You can create your own field type if needed.
wp_wpl_sort_options: List of available sort options for certain kinds.
wp_wpl_item_categories: Categories for wp_wpl_items table.
wp_wpl_room_types: Rooms Type for properties.
wp_wpl_locationtextsearch: Cached location information of property for using in WPL autocomplete. (Using Google auto suggest is recommended.)
wp_wpl_setting_categories: Category of WPL settings fields.
wp_wpl_kinds: Available kinds/entities for WPL. 0 means property and 2 means user. By installing Complex or Neighborhood etc. addons you may have more kinds in this table.
Note: We used category in different tables in wpl so you can check following descriptions to make it clear.
wp_wpl_dbcat: Categories of the WPL fields (wp_wpl_dbst table). For example, Basic Details, Gallery, Address Map
wp_wpl_property_types: Categories of property types is in this table, Records with parent:0 are categories. For example: Residential, Commercial, Land.
wp_wpl_listing_types: Categories of Listing Types, Records with parent:0 are categories. For example: Sale, Rental, Vocational.
wp_wpl_item_categories: Categories for wp_wpl_items table. For example: gallery, attachment, etc.
wp_wpl_setting_categories: in WPL backend we have settings, Each settings have a category for example: Global, Gallery, ... , UI Customizer.