We don't even have a shred of a clue how to do that, only prevent it, and it may well be a bit late to meaningfully prevent.

As someone with 0 knowledge on this. Why is it late and is there any hope one day to be able to reverse the acidity of the oceans?

The problem is the sheer scale, both in terms of quantity of dissolved CO2, and time.

I think the (second part)of this does a better job explaining just how and why than I would though:

http://www.ibtimes.co.uk/reversing-ocean-acidification-aggre...

I think the difference between acidity due to sulfur dioxide and CO2 is twofold.

Sulfur dioxide is reactive and gets rapidly cleared in the environment. Sulfur dioxide + H2O -> sulfuric acid -> acidic rain -> + just about any metallic element -> sulfate[1]. So a hang time of 'years' vs CO2 hang time of thousands of years.

Second the amount of CO2 we're releasing is probably two orders larger than the amount of sulfur dioxide we were releasing back in the 70's. Since raw coal and petroleum contains a fractional percentage of sulfur it stands to reason the CO2 produced is probably 100 larger than SO2.