“What do you do?” or “What is your job?”

 When someone asks you “What do you do?“, they’re asking about your job. In English, people don’t actually say “What is your job?“. Instead they say “What do you do?“ and the correct response is “I’m a/an + a job title”.

Examples:

• I’m an English teacher.
• I’m a dentist.
• I’m a lawyer.

“What is your job?“ is still used in English textbooks, but in real life native English speakers almost never say that. They will mostly say:

• What do you do?
• What do you do for a living?
• What do you do exactly?

from: https://learnenglishwithdemi.wordpress.com/2016/01/02/what-do-you-do-or-what-is-your-job/