know from one to the other
The Spanish phrase 'saber de pe a pa' translates to 'know something like the back of one's hand' in English. It is used when somebody has a comprehensive and thorough understanding or knowledge of a subject matter or task. Literally, it refers to knowing something from P (the first letter of the Spanish alphabet) to P (the last letter of the Spanish alphabet), illustrating the idea of knowing everything about something from start to finish.
She knows the system inside out.
This phrase indicates that she has a thorough understanding of how the system works.
The teacher knows the city's history inside out.
This suggests that the teacher is very knowledgeable about the city's history.
He knows the rules of the game inside out.
This implies that he is well-versed in all the rules that govern the game.