DDR = Double Data Rate
This indicates that it transfers data twice each clock cycle.
DDR3 = RAM that is compliant with the third revision of the DDR standard.
It offers lower power usage, higher bus rates and higher data transfer rates than previous revisions, somewhat offset by higher timings.
2GB = The capacity of the DIMM (Dual Iin-line Memory Module, AKA stick of RAM).
PC3 = Again indicates that this is DDR3 RAM.
PC3-8500 = The peak data transfer rate in MB/s.
The rest is irrelevant.