One of the major responsibilities you will have as an adult is to take care of your money. You will get a job, receive a salary and try to live with it month by month. Perhaps, you will try to put some away on the side, as a precaution; savings are always a good idea. Unfortunately, not everyone learns, or knows how to manage their finances.
Usually, people spend the majority of their salary before the end of the month. Sometimes, they even neglect to pay their bills because they found some other, usually shiny thing to spend the money on. These are examples of what an irresponsible person does.
If you want to be taken seriously, and live a normal life, you will need to learn how to deal with money. You should pay all your bills when you get your salary. Then, buy groceries and make a plan on how you will use the rest. You should also have some money in your savings account or, maybe you could invest part of it. Both of these are better than spending recklessly, which can lead to debt and other problems for you.