This is the 104th most frequent Vietnamese word.
cho
"Cho" in Vietnamese means "give" or "for."
In this sentence, 'cho' functions as a preposition meaning 'to', indicating the recipient of the action.
Tôi tặng quyển sách này cho bạn.
I give this book to you.
In this usage, 'cho' is part of an imperative phrase meaning 'give', requesting the action of providing a glass of water.
Làm ơn cho tôi một ly nước.
Please give me a glass of water.
Here, 'cho' is used as a preposition meaning 'for', showing that the new shirt is intended for the speaker.