off
The German word 'ab' is a preposition that can be translated to 'off' in English. It is used to indicate separation or removal from a location or state. For example, 'Ich nehme den Hut ab' means 'I take off my hat'. However, 'ab' can also be used as a prefix in compound words to express a sense of removal or negation, such as 'abnehmen' (to lose weight).
From tomorrow I will do gymnastics.
This sentence shows the use of 'ab' to indicate the starting point of an activity. It means 'from tomorrow onwards, I will start doing gymnastics'.
I am staying at home from now on.
This sentence uses 'ab' to signal the beginning of a new situation. It is often used in this way to mark a change – in this case, the change is that the speaker will stay at home from this point forward.
He is on vacation from Monday.
In this example, 'ab' is used to signify the onset of a period of time. The speaker is saying that, starting on Monday, the person in question will be on vacation.