In the film "Parasite", how does the poor South Korean family, named Kim, make a day-to-day living?

"Parasite" is a 2019 South Korean black comedy thriller film, directed by Bong Joon-ho, who co-wrote the screenplay with Han Jin-won and co-produced the film. This film won four awards at the 2018 Oscars including best picture. The movie stars Song Kang-ho, Lee Sun-kyun, Cho Yeo-jeong, Choi Woo-shik, Park So-dam, Jang Hye-jin, Park Myung-hoon, and Lee Jung-eun. It follows a poor family (Kim) who scheme to become employed by a wealthy family (Park) and infiltrate their household by posing as unrelated, highly qualified individuals.

At the start of the film, the Kim family—father Ki-taek, mother Chung-sook, daughter Ki-jung, and son Ki-woo—live in a small semi-basement apartment (banjiha) in Seoul. They have low-paying temporary jobs folding pizza boxes, and struggle to make ends meet. University student Min-hyuk (Park Seo-joon), a friend of Ki-woo's, gives the family a scholar's rock meant to promise wealth. Leaving to study abroad and knowing his friend needs the income, Min-hyuk suggests that Ki-woo pose as a university student to take over his job as an English tutor for the daughter of the wealthy Park family, Da-hye. Ki-woo pretends to be a Yonsei University student and is subsequently hired by the Parks.

The entire Kim family will scheme to get each member of the family a job as servant with the Park family. They will pose as unrelated and highly qualified workers for the jobs in question.