Hi Yinan! If you say, “Let’s finish today,” that means you want to finish your whole project today. If you say, “Let’s finish for today,” you mean that you want to stop working today and resume your work tomorrow.

As for how to end a meeting politely, if you change the phrase to a question you can make it more polite. For example, you can say, “Shall we finish for today?” This is a suggestion instead of a command.

You could just say: “Let’s finish for the day” “That’s good/enough/good enough for today” You could also add an “okay” or “alright” at the beginning as a sort of cushion, and as far as being polite, you’ll have to rely on your tone for this kind of sentence. Just try saying “That’s enough for today” angrily, and then try saying it calmly. It can be understood differently depending on how you deliver it. “For today” would mean that you are going to continue working on it on a future date. “Today” would mean that you need to finish on this day and you do not plan to work on it in the future. Ex: “Let’s finish FOR THE DAY and pick up where we left off on Wednesday” vs. ”Let’s finish TODAY so we don’t have to work on it again in the future”

Let’s wrap it up for today. Let’s leave it here, for now.