What is meant by the two functions of in breathing and out breathing? Thank you
Did you read about it in any specific translation of a specific EBT?
I can’t recall reading the term function in the usual descriptions of mindfulness with breathing in the text.
Are you asking about what exactly is in breathing and what exactly is out breathing?
Just by noticing the breathing in and breathing out, you can only improve you health but not your morality.
The deeper meaning of Anapanasati is ana (same for assasa) is taking in what is good (see note1) and pana (same for passasa) is discarding what is bad (see note1). This will change your gati (habit/character) if you practice it for 24 hours a day and over a long period of time, you will notice that your morality has improve tremendously. This gati will prepare you for the stages of Nibbana.
Note1: See Dhammapada verse 183.
Etaṃ buddhana sasanaṃ