The phrase "to prop up" means to support or maintain something that is weak, failing, or in danger of collapsing. It can be used both figuratively and literally. Figuratively, it refers to providing encouragement, assistance, or resources to help someone or something survive or continue despite difficulties or setbacks. Literally, it means to provide physical support for an object or structure that is unstable or in danger of falling over by using a prop such as a pillar, beam, or other temporary measure.