SQL Server 2012公共服务器角色

I have a login "user2" who is assigned to "Public" server role. Does this mean the login will not be able to access any database? The weird part is that, the login is able to access 3 out of 9 databases on the server. I'm not sure if there's some setting on the database which I need to change or is it the public role I need to look into. Any help and explanation would be appreciated. ThanksI have a login "user2" who is assigned to "Publ