Learn Polish: Nie czytam, bo jestem zajęta. - I am not reading because I am busy.

bo means "because" and connects two parts of a sentence. In Polish, it is a strict punctuation rule to always put a comma before conjunctions like bo (because) and że (that).

Where is the word for "I" in this sentence?

You don't need to say ja (I) because the verb endings already show who is doing the action. Both czytam (I am reading) and jestem (I am) end in -m, which signals the "I" form. You only add ja if you really need to emphasize it.

I learned the word for "busy" as zajęty. Why is it zajęta here?

Adjectives change their endings to match the gender of the person they describe. Because the word ends in -a (zajęta), we know the speaker is female. A male speaker would say jestem zajęty.

Can Nie czytam also mean "I don't read"?

Yes! Polish doesn't have a separate tense for actions happening right now (like "I am reading" in English). Nie czytam can mean "I do not read" or "I am not reading", and you just use the context to tell the difference.