What is connection time?
As per the help section on their website, they describe Connection Time as the following:


  Connection Time: Displays the time taken to get connected to the SQL database server.


From that brief description, I'd be willing to say that it is the time duration between initiating the connection to the SQL Server instance.

If this is the case, then the impacts here would be the physical network latency and the server capabilities for a client response.  For further investigation into this metric, I'd consult the actual vendor for more details and acceptable statistics.