It looks like bacterial leaf spot, most likely from a period of high humidity. If humidity decreases it may stop spreading by itself but the worst of the leaves might as well be removed.
If they're all like that then I'd just isolate the plant instead as they will produce a bit of energy for growing new leaves until they get bad enough to fall off on their own, but once you have new leaf growth you don't want that touching them, and you don't want to let the infected leaves get wet from rain or watering as that will spread it.
If the only ones infected are lower leaves then it may have splashed up from the soil.