This lesson will introduce you to the concept of variables in programming. The best example that I can think about to explain the concept of variables to you is that of the Prime Minister of India. Different people hold the post of the Prime Minister of India at different points in time. The current prime minister at the time I am writing this is Narendra Modi. Before him it was Dr. Manmohan Singh. Before Dr. Manmohan Singh, it was Atal Bihari Vajpayee. And maybe 10, 20, 30 years down the line we will have new people take up the post of Prime Minister of India.
So, you can think of Prime Minister of India as a variable whose value can change from time to time.