The new messaging option allows you to message directly your customers from the local listing of the the Google search and the Google map.
Google was testing the feature in the November last year and now it is out in the united states at the moment.
This option is present in the left side of the homepage of Google my Business and another option of message with customers in the middle.
On clicking the link in the information provided by the Google search results, it will set up a Google my business account for messaging.You need to provide a mobile number which you can receive SMS and will be readily accessible for responding to customers.
The option also tells the expected response time from the business sites which can be seen on the bottom side.