First let’s deal with the pronunciation. The “i” and the “y” are pronounced like the “i” in “bit”, “pit”, and “sit”. The “z” sounds like the “s” in “sit” and “sip”; the main stress is on the first syllable. “Ditzy”, or “ditsy” as it is sometimes spelt, is a word that is usually used in American English in informal contexts. The word is normally used with women. When you refer to a woman as a “ditz” or “ditzo” what you mean is that she is very scatterbrained. She is quite silly and is not very well organised.
Here are a few examples. *Hey Rahul, it’s that ditzo Jaya on the phone. Do you want to talk to her? *My ditsy cousin forgot to post the invitations.