The details matter.
I am not familiar enough with Canadian criminal law to begin sorting out how it works in specific cases.
The reason I mentioned that a prohibition continues while the person is on probation (even if the conviction itself for a summarily prosecuted hybrid offence does not constitute a prohibition) is that it is my impression that any of the impaired driving convictions ordinarily result in some period of probation. But you are not the first to report here that there was no probation, so apparently that happens.
These kinds of cases appear to still be rather casually prosecuted in Canada compared to the U.S. and some European countries. Which can lead to confusion. The level of confusion also appears to be sometimes aggravated by less than fully honest descriptions given to clients by lawyers (especially public defender type lawyers), who may be encouraging a plea by the defendant and thus minimizing some of the wrinkles.
BUT all that said, if there is NO probation for sure, and the lawyer says the conviction is for a summary offence, and for example you were never presented with an indictment, the odds are high that it was indeed prosecuted summarily.
Thus, if prosecuted summarily, and there is a final disposition, a conviction, as such, and there is no term of incarceration or probation, that means:
-- it is not a conviction for an "indictable offence" under Section 22(2) in the Citizenship Act, and thus does not constitute a prohibition, EVEN THOUGH
-- the same conviction would be considered an "indictable offence" for purposes of Section 36(1) and 36(2) in IRPA, which would make a Foreign National inadmissible (subject to rehabilitation provisions)
BUT again, what matters, what makes a difference, is what your specific court record shows.
Also Note:
It is very likely there is, nonetheless, a criminal record which will pop up when IRCC processes your Citizenship application. So it may be prudent to disclose the charge and in the explanation box describe the outcome even though it is not a prohibition. Just the initial charge is something which appears to trigger a finger print request and may result in some additional non-routine processing, thus taking a little longer than routinely processed applications. But so long as there is a final disposition (if anything is still pending, WAIT to get all resolved before applying for citizenship), even though it is a conviction for a hybrid offence, and so long as it was actually prosecuted summarily and you are NOT on probation, you should be OK.