macbook air read sdhc cards/

It will read and write them just fine.

The only caveat is, that since the SD reader on the MBA is mated to a USB 2.0 bus, the read and write speeds will be at the SD card specification, and not the faster SDHC spec.

The 13-inch Air has an SD slot that reads SDHC cards. The 11-inch Air doesn't have an SD card slot at all, and requires an external card reader.