An occupation is a means of employment.
In English, we tend to ask people “What do you do?" rather than “What’s your job?" though the latter is acceptable. Note the answer is generally “I’m a [job title]" e.g. “I’m an English teacher", though we can also respond with a verb, e.g. “I teach English.” We don’t usually ask this question to children since it’s generally safe to assume that they’re students.
English language learners often need to be able to give their occupation at beginner level. If the teacher doesn’t speak the student’s L1, and the student doesn’t know the English translation of their occupation, cue hilarity in trying to work out what on earth a student does for a living. This can be a good learning point as it can be the first phrase that a student researches and teaches themselves.
Note if a student is unemployed, this can be a point of shame, and its discovery needs to be dealt with sympathetically.
Occupations can also result in occupational stress.