Single one to give you an explanation:
Ver 2.1: indicates that this version is 2.1
PCI: It could be the computer's PCI slot.
PCI slots are expansion slots based on the PCI local bus (Pedpherd Component Interconnect, Peripheral Component Expansion Interface), which are generally cream in color and are located on the motherboard below the AGP slot and above the ISA slot. It is 32-bit or 64-bit wide, operates at 33MHz, and has a maximum data transfer rate of 133MB/sec (32-bit) and 266MB/sec (64-bit). PCI slot is the main expansion slot of the motherboard, through the insertion of different expansion cards can be achieved by the current computer can realize almost all the external functions. The main features of the PCI Express are the following