The concept of abstraction in programming is a method in which certain things, that may be viewed as unnecessary are hidden from the user, and only what is needed is shown. A general example can be; using a computer, when we hit a key the computer takes input and it gives output, but behind the scene there are thousands of background tasks going on to make the usage of the system a success, we do not see it, and we don't need to as they are not important to us.
These tasks are hidden from the user. An example in programming is declaration of variables in a class. This can be hidden from the user and all the user see is the program asking for input or taking argument that has been passed. The actual declaration of the data type is hidden from the user.