This is the 148th most frequent Vietnamese word.
gửi
"Send" or "submit."
In this sentence, 'gửi' means 'to send', indicating the act of dispatching the letter to someone.
Tôi gửi bức thư này đến bạn tôi.
I send this letter to my friend.
Here, 'gửi' is used metaphorically to represent expressing or communicating greetings.
Xin gửi lời chào đến gia đình bạn.
Please send greetings to your family.
In this usage, 'gửi' signifies expressing gratitude metaphorically.