to know
In Italian, 'sapere' is used to express knowledge or understanding about something, it is also used to ask if someone knows something. For instance, 'Tu sai' (You know). It's also used to say you can do something, like: 'Io so nuotare' (I know how to swim).
You must know that I do not agree with you.
The phrase 'devi sapere' translates to 'you must know', indicating a necessity or obligation to be aware of the following information.
Mario wants to know where you were yesterday.
In this sentence, 'vuole sapere' means 'wants to know', expressing someone's desire to obtain a specific piece of information.
We cannot know what will happen tomorrow.
The phrase 'non possiamo sapere' translates to 'we cannot know', suggesting the impossibility to predict or foresee a future event.