Learn Spanish (Latin America): Hola y adiós.

Yes! Hola and adiós are universal. You do not need to change them based on who you are talking to. You can say hola to your best friend (tú) or a stranger (usted).

Is the "h" in hola pronounced?

No, the letter "h" is always silent in Spanish. You pronounce hola exactly as if it were spelled "ola" (OH-lah).

How do you pronounce the word y?

When y is a word all by itself meaning "and", it is pronounced exactly like the English vowel sound "ee" (as in "see" or "bee").

Why is there an accent mark over the "o" in adiós?

That accent mark tells you to put the strongest stress of your voice on that vowel. So you pronounce it ah-DYOS. If it did not have the accent mark, the natural pronunciation rules of Spanish would make you stress the first syllable instead.