annyeong haseyo = Hello. / Hi. / How are you? / Good afternoon. / Good evening. / etc..
annyeong = well being, peace, health
haseyo = you do, do you?, please do
annyeong haseyo is the most common way of greeting someone in Korean, and annyeong haseyo is in jondaetmal, polite/formal language. When someone greets you with annyeong haseyo , you can simply greet the person back with annyeong haseyo.
gamsa hapnida / kamsahamnida = Thank you.
gamsa = appreciation, thankfulness, gratitude
hapnida = I do, I am doing
gamsa hapnida / kamsahamnida is the most commonly used formal way of saying “Thank you.”kamsa/gamsa means “grati-tude” and hapnida/ hamnida means “I do” or “I am doing” in jondaetmal, polite/formal language, so together it means “Thank you.” You can use this expression, gamsa hapnida / kamsahamnida, whenever you want to say “Thank you.” in English.