This is the JSP page directive (more info).
The first line creates an instance of Bean.User class (if one doesn't exist in application scope, more info about jsp:useBean can be found here) and then the second line sets any properties of the User class to matching request parameters (mode info about jsp:setProperty can be found here). So if the request had a parameter named age, and the User class has setAge method, then the setAge method is called with the value of the age request parameter...