This is the 108th most frequent German word.
davon
"Of it," "from it," or "about it."
Here, "davon" refers to a subset of the apples that were mentioned earlier, indicating 'of them' or 'of those'.
Ich habe fünf Äpfel, aber drei davon sind faul.
I have five apples, but three of them are rotten.
In this sentence, "davon" points to something that has been referenced earlier in the conversation or context, meaning 'of it' or 'about it'.
Er wusste nichts davon.
He knew nothing about it.
Here, "davon" is used to express what the speaker dreams about, translating to 'of it' or 'about it'.