‘Leave’ is used for both people and transport ‘going away from’ but ‘depart’ is usually reserved for transport: The train departs at 6 pm and we also have the word ‘departure’ as in ‘departure times’ and the opposite meaning ‘arrival times’.
Hi Saneta, I’m not sure I understand your question. Do you mean to ask if early today means early in the morning? Yes, early today means in the early morning.[YSaerTTEW443543]
The speaker is saying that he cannot allow the other person to leave early. (Note that there is no indication that this is morning. In fact, the most likely scenario is a worker asking his boss if he can leave work early… for example, if he can possibly finish work at 4 p.m. instead of 5:30 p.m. or similar)