To enable, navigate to Network-wide > General and set "Traffic analysis" to "Detailed: collect destination hostnames". This will add Traffic Analytics to your Monitor tab the next time you refresh.
Network-wide > Monitor > Traffic Analytics
This page aggregates all of the detected applications for a given time frame. This time frame can be selected at the to of the page and options for weekly, daily and monthly are available. Custom pie charts can also be configured to further customize the data based on HTTP hostname, IP, Port range, etc. This is configured under Alerts & Administration.
Hostname Reporting
Meraki's layer 7 application visibility is now enhanced to dynamically detect applications running on your network and provide hostname visibility. This is an opt-in feature and can be enabled under Network-wide > General.