This is the 828th most frequent Vietnamese word.
lượng
"Quantity" or "amount."
In this sentence, "lượng" is used to indicate a quantity or amount of something, specifically of water in this case.
Tôi cần một lượng nước đủ để ăn canh.
I need a sufficient amount of water to make soup.
Here, "lượng" is employed to describe the quantity of knowledge that the person possesses.
Anh ấy có một lượng kiến thức sâu rộng về lịch sử.
He has a substantial amount of knowledge about history.
"Lượng" in this context refers to the measured quantity of an environmental factor, namely rainfall.