However, it's important to understand the context in which it's used because the phrase can be interpreted in various ways depending on the situation.
Here are some possible interpretations:
* As a warning: This phrase can be used to warn someone about a potential problem or danger. For example, "Sepa la madre que si no te pones las pilas, vas a reprobar" (Let the mother know that if you don't get your act together, you're going to fail).
* As a sarcastic remark: The phrase can be used sarcastically to express disbelief or disapproval. For example, "Sepa la madre, a mí no me engañas" (Let the mother know, you're not fooling me).
* As a playful phrase: The phrase can be used playfully among friends as a way to express amusement or surprise. For example, "Sepa la madre, no te la creí!" (Let the mother know, I didn't believe you!).
The meaning of "Sepa la madre" will depend on the tone of voice, the context of the conversation, and the relationship between the speakers.