Bean class /encapsulation means variable should be private & getter & setter should be public. Because of the reason data hiding.Anybody can't access this variable out side.

My Question is :`With the getter/setter method we can access/set variable from outside class.Then why we need to keep that variable private && how we can tell this is data-hiding? 

Actually i like to get some explanation because , without any idea just i am doing project like this.
Please if there are any mistake or unclear question, please forgive me. 

Please anybody explain this. 

Thanks in advance