Usually people enter your site through many different pages, not just the main page. Web-Stat shows you what percentage of your total traffic enters through each one of these entrance pages for the current month. Previous months data is available from the archive bar above the report.
Entrance pages can be listed in different ways (use the menu above the report):
The Monthly Entrance Pages report also includes, for each one of your entrance pages:
The three metrics above are very important in comparing the quality of your entrance pages. In general, the higher the average visit depth and time on site, and the lower the bounce rate, the better the entrance page was at capturing the interest of a visitor. On the contrary, a poorly designed entrance page will generate high bounce rates, low visit depths and low time-on-site (note that this is true in general, but there are special cases where it could be argued that a high visit depth/time-on-site is not a good thing as it might indicate that visitors have difficulty finding the information they are looking for
For your convenience, the time-on-site, visit depth, bounce rate and conversion percentage columns are color-coded to identify deviation from the site's average. Pink cells indicate results worse than average while green cells indicate results better than average. The deeper the color the greater the deviation from average. Some cells are colored yellow, meaning that there is not enough data to make them statistically relevant.
Note that you can also view the entrance pages for individual visitors from the visitors details report, available from the main stats menu: