It uses the SPI bus with a Quad I/O interface, meaning it can shift data four bits per clock cycle instead of the traditional one. That matters when you need to boot a microcontroller or stream firmware updates without waiting on a slow serial link. The 108 MHz clock rate translates to a practical read throughput well above what a single-bit SPI part delivers, which is the main reason designers pick this class of memory over older serial Flash parts.
Infineon no longer manufactures it as a standard production item. If you have this on a BOM for an active design, you are looking at last-time-buy inventory or surplus-channel sourcing.