If you check "Public", your stats will be accessible to anyone, simply by clicking on your counter. Access can also be granted without the need for a password through a URL like :
http://www.web-stat.com/stats/userID.htm (where userID is your account's user ID).
If you check "Private", your stats will be password-protected and you will only be able to access them by clicking the 'Check Stats' link on the Web-Stat menu bar and entering your user name and password. Clicking on your counter will simply take you to the Web-Stat main page.
Your stats can be changed to Public or Private at any time in the Control Panel.