Social · Philippines
Add "po" or "opo" to sentences when speaking to elders or people in authority — it's the polite form of address in Filipino.
When you answer a question from an elder or a superior, end your sentence with “po” — for example, “Salamat po” (thank you) or “Opo” (yes, respectfully).
You don’t need to use it with friends or people your own age, but when in doubt with someone older, adding “po” is always the safer, more respectful choice.
Filipino has built-in politeness markers. "Po" is added to the end of sentences when speaking to someone older or in a position of respect, and "opo" is the polite way to say "yes." Dropping them with elders can come across as rude or overly familiar, even if the words themselves are correct. In parts of the Southern Tagalog region you'll also hear "ho" used the same way — it's a regional variant, not a mistake.
Source: Po and Opo – Wikipedia