अट्ठु पवयणमायाओ, समिई गुत्ती तहेव य ।
पंचेव य समिईओ, तओ गुत्तीउ आहिया ॥२४.१॥
The mothers of the teaching are eight — five forms of carefulness (samiti) and three forms of self-control (gupti).
The opening verse announces the subject of the entire chapter: the eight mothers of the teaching. These eight practices are called "mothers" because they give birth to the spiritual path and protect it from destruction — just as a mother gives birth to a child and nurtures it. Five are forms of active carefulness, governing how a monk should conduct himself when engaging with the world. Three are forms of self-control, governing how a monk should restrain himself from harmful activities. Together, these eight form the complete foundation of monastic discipline. Without them, no amount of knowledge or faith can bear fruit in practice.
The simple version: The spiritual path has eight foundational practices — five about being careful in your actions and three about controlling yourself from within.