Describe a person whose job is important to the society.
You should say:
who this person is
what job he or she has
how you know this person
and explain why his/her job is important to the society.
Let me tell you about my friend whose job, in my opinion, is critically important and indispensable in every part of the society. He is an IT engineer. He has been working in this industry for over ten years to accumulate the necessary working ability and experience. We got to know each other because we are neighbours, so we can meet frequently.
I think his job is really important because nowadays, the whole country, including the various business and non-profit organisations, are running on the IT systems. So he should shoulder the responsibility to develop and maintain the system operating smoothly and can, of course, work under great pressure.
Moreover, as far as I know, IT engineers need to design, develop the core systems of many other industries such as banking, insurance, telecommunication, manufacturing and so on, which heavily rely on their information systems to operate their own business. Therefore, I guess their systems are the driving force behind their business and so are essentially important to them.