Learn Danish: Han blev selvstændig efter tyve år i firmaet. - He became self-employed after twenty years at the firm.

It means both! Its literal translation is closer to "independent" (from selv meaning self, and stand meaning stand). In a work context, it means you have your own business, but you can also use it to describe an independent person or a sovereign country.

Why is there no article like en before selvstændig?

When describing a person's profession, nationality, or status with verbs like at være (to be) or at blive (to become), Danish usually drops the indefinite article (en or et). Here, selvstændig functions as an adjective describing his new status.

Why is the preposition i used in i firmaet rather than på, which we often see with workplaces?

While på is used for physical workplaces like an office (på kontoret) or a factory (på fabrikken), Danish uses i when referring to a company as an organization or abstract entity, such as i et firma or i en virksomhed.