If you are just interested in a report, there are some limited report available under the Admin menu - Site Log.

Alternatively, you can use the report module (or similar)  to report this information.   You will need to create the appropriate SQL query to match your requirement.   You will need to determine the what a "user" is and what a "visit" is ...  I use

select
 convert(varchar,DateTime,102) as [Date],
 count(SiteLogID) as [Views],
 count(distinct dbo.SiteLog.UserHostAddress) as [Visitors]
from dbo.SiteLog
where
  PortalId = [DNN:portalID]
  and dbo.SiteLog.DateTime
    between convert(varchar, dateadd(d, -29, getdate()), 102)
        and convert(varchar, dateadd(d, -1, getdate()), 102) + ' 23:59'
group by convert(varchar,DateTime,102)
order by Date desc

The above select return a list of dates with the number of users and Views.  I graph the results  - see here 

I consider for this report -- a user is a unique ip address, and a view as a page request.

Hope this helps
Paul.