This option enables support for PCI ENE CB710/720 Flash memory card reader found in some laptops (ie. some versions of HP Compaq nx9500). You will also have to select some flash card format drivers (MMC/SD, MemoryStick). This driver can also be built as a module. If so, the module will be called cb710.
This is an option for use by developers; most people should say N here. This adds a lot of debugging output to dmesg.