JavaBeans Specification emerged from AWT/SWING frameworks. It defines a standard way of how your encapsualted data should be set or retrieved from an object.
Getter and setter methods were created so that any engine/framework could query for the data dynamically without knowing about the object's methods.
JavaBean specification has also been extended to Java EE. A good example is JSP page using a useBean tag. The bean has getter and setter methods and the jsp container displays/reads the properties and renders the page dynamically for you.
You could refer to petsore web application or any Java Swing sample application to get a better understanding of java beans.