In procedural program(C, Pascal, etc.), programming logic follows certain procedures and the instructions are executed one after another. In OOPs program, unit of program is
Object, which is nothing but combination of data and code.
In procedural program, data is exposed to the whole program where as in OOP's program, it is accessible within the object and which in turn assures the security of the code.
In order to clearly understand the object orientation, let’s take your “hand” as an example. The “hand” is a class. Your body has two objects of type hand, named left hand and right hand. Their main functions are controlled/ managed by a set of electrical signals sent through your shoulders (through an interface). So the shoulder is an interface which your body uses to interact with your hands. The hand is a well architected class. The hand is being re-used to create the left hand and the right hand by slightly changing the properties of it.