This is an OK “disease of the week” episode, but there isn’t enough long-form plot and character development to pique our interest for a full synopsis/analysis.
Basically, everyone on the station (beginning with Irishy O’Brien, no surprise there) becomes infected with an “Aphasia Virus” that makes them speak gibberish. The virus originated with some sort of device that altered any and all replicated food at the molecular level, and quickly mutated to become airborne. Kira naturally thinks the Cardassians are behind it, but it turns out that the Bajoran resistance (who were forced to build the station) snuck in the device as a really epic terrorist move. She has no choice but to track down the guy responsible, infect him with the virus, and then force him to help cure everyone. Don’t push Kira, guys.
Meanwhile, back on the station, everyone is quarantined, but there’s this dick of a freighter captain who wants to take off before his cargo spoils, and he almost blows up the station trying to get away. The only people on the station as yet unaffected by the virus are the unlikely Quark/Odo teamup, who save the day. When Kira comes back to the station, Quark answers her hail from Ops, which is a pretty funny moment.
Then Bajoran Resistance Guy creates an antidote (I find it implausible that Bashir couldn’t cure everyone even while speaking nonsense) and everything’s back to normal. It’s not a bad episode, by any means, but it’s not a great one either, and no one (least of all us) will blame you if you skip it.
And that’s what you missed on: that episode we didn’t particularly want to watch.