AC charging refers to charging where the AC (alternating current) power in the electrical grid gets transformed into DC or direct current (which is what an EV's battery stores) through a converter in the car. This makes it slower than DC charging, where the converter is in the charger itself and thus can be of much higher capacity because there are no space constraints.
As a consequence, you'll find AC chargers in private settings - at home, at the office, that sort of thing, where you can leave the car on the charger for a longer period of time. Most private EV charging stations can deliver from 11 to 22 kW (assuming the presence of a main fuse with a rating of 3 x 32 A, or amps, for the latter). That said, it is still very common to see 1.7kW / 1 x 8 A and 3.7kW / 1x 16A chargers installed.
The actual speed of charging will depend on what the limiting factor is - either the charging station itself (as described above), or the car's capacity to convert AC to DC. Most EVs support 11kW AC charging by default, but for a lot of models you need to pay extra for a 22kW charging cable. Our spec page tells you what the maximum supported AC charging is for a particular model, and an estimate of how long it would take to fully charge on such a charger.