TOPIC: Could you please tell me which one is correct?

I come across a sentence from a book."She knows a thing or two about Italian". There are a few guesses on the meaning. Could you please tell me which one is correct?
1.She knows a little bit about Italian language.
2.She is quite good in Italian language.
3. She knows quite well about the Italian culture.
Thanks and regards

"A thing or two" means some matters, facts or information. If someone " knows a thing or two", they have some knowledge about something, but they don't have in-depth knowledge.
Here's an example sentence:
Why don't you ask Andrew about it? He knows a thing or two about (= has some knowledge of ) Computers.
Your definition 1is the closest meaning to the original sentence.