What does cleaning outsourcing mean?

That is, the cleaning work that is not the responsibility of the staff of this unit is undertaken by a third party. Of course, according to the requirements of this unit, people have to be given money to carry out cleaning tasks and meet the standards.

For example, many companies work in a building, so the building itself is a property, and there are cleaning companies, so each company can choose whether to find cleaning services in the building or choose cleaning by itself.