What does "have you ever been convicted of a criminal offense that has not been dismissed upon condition of probation" mean?

I haven't seen the document, but based on what you wrote, you should answer YES. That's probably not what you want to hear.

Oftentimes people will seek Penal Code 1203.4 relief upon completing the terms and conditions of their probation. That relief is commonly referred to as an "expungement," but that is a misnomer. While the relief does turn a conviction into a dismissal and provides the recipient the ability to lawfully assert to private sector employers that he/she has never been convicted of the charge for which the relief is granted, the individual must admit to public sector employers that they received a dismissal pursuant to PC 1203.4. I suspect that you might be applying to a private sector (non-government) employer, and because applicants wouldn't have to tell that employer about any convictions that had been granted 1203.4 relief, the employer is asking specifically whether you've ever had any convictions that have not been 1203.4'd. It sounds like you have not obtained the PC 1203.4 relief. Because the DA's office has to be served and given time to respond, it'll take a little less than a month to complete the process start to finish. Consider filing the petition if you think your prior conviction will jeopardize your chances of landing the job and you can hold off a bit on submitting the application. You can handle the PC 1203.4 petition yourself or hire an attorney. If you 1) have successfully completed the terms and conditions of probation; 2) are not currently on probation or serving a sentence; and 3) are not facing any other criminal charges, then you have a right to withdraw your guilty plea, insert a not guilty plea, and your case will be "dismissed." There are other caveats to this relief (for instance if you are facing another DUI in the next 5 years, your earlier DUI would still be a prior even if you obtained 1203.4 relief), and you can read the statutory language at https://www.dmv.ca.gov/portal/dmv/?1dmy&urile=wcm:path:/dmv_content_en/dmv/pubs/vctop/appndxa/penalco/penco1203_4. It's fairly self-explanatory. Further, there will be an accompanying fee for the process (it varies depending on the location, but roughly $120). Best of luck with everything.

Yes, you have been convicted of a DUI. It was not dismissed.

That is a very unclear question; it really makes no legal or grammatical sense. It may mean: If you have a conviction that has not been dismissed pursuant to 1203.4 PC (expungement), then please tell us. If I were you, I would either hire a lawyer and have him or her counsel you through this, or I would ask the prospective employer what that question means and go from there. From my experience, prospective employers are more likely to hire a forthcoming applicant especially if the conviction is minor like VC 23152(A) (DUI).