Learn Hardcore Hebrew: אני לא רוצה לשכוח את הספר בבית. - I do not want to forget the book at home.

Yes, Hebrew can often omit the subject pronoun in casual speech if it is clear from context, so לא רוצה לשכוח את הספר בבית is possible in conversation.

But in this sentence, אני makes the subject explicit: I do not want to forget the book at home.

This is especially helpful because רוצה in unpointed Hebrew spelling does not clearly show person by itself. It can mean:

I want
you want
he wants
she wants

So אני removes the ambiguity.

What does לא רוצה mean as a unit?

לא means not, and רוצה means want/wants.

So:

אני רוצה = I want
אני לא רוצה = I do not want

In Hebrew, negation with לא usually goes directly before the verb or verb phrase it negates.

Why is there a ל at the beginning of לשכוח?