'What is your job?', is grammatically correct but not usually the way we ask someone's occupation. Instead we ask, 'What do you do?' or the longer form, 'What do you do for a living?'
Some common ways to answer are:
I'm a doctor/ teacher / artist.
I work for EC/Adidas/Vodafone - company name
I work in a bank/coffee shop/factory - type of business/industry
I work on a farm/boat/oil rig - we use the preposition on with these types of locations and industries.
A person who + verb
What's a baker? A person who makes bread.
What's a cobbler? A person who fixes shoes.
What's a vet? A person who treats sick animals.
What's a florist? A person whose job is to sell flowers.
Now answer these questions: