Imagine you want to give your friend some money, but you don't want to use cash or a credit card. Instead, you go to your bank and ask for a piece of paper called a demand draft. On this paper, you write your friend's name and the amount of money you want to give them.
Then you give this paper to your bank, along with enough money to cover the amount of the draft. The bank takes your money and puts it in a special account. This account is used to guarantee that your friend can cash the demand draft without any problems.
Your friend then takes the demand draft to their bank and gives it to a teller. The teller checks to make sure that the draft is authentic and then gives your friend the money.
So a demand draft is like a special piece of paper that you write on to give money to someone else, and the bank makes sure that the money is available for the other person to collect.