Not exactly sure what you’re looking for help with.
The value that you gave is how ACF stores the value for this field. This is not a JSON value, it is a serialized array. You can get more information on this by starting here http://php.net/manual/en/function.serialize.php.
The value stored by ACF is used to display maps on the front end of the site using the documentation here https://www.advancedcustomfields.com/resources/google-map/
Not exactly sure what it is you’re trying to do. If you explain more I might be able to provide more help.
