Mercury is much closer to the Sun than us, and makes one orbit every 88 Earth days. Mercury's apparent retrograde motion (aka Mercury Retrograde) happens when Mercury is passing us. For this short period, it appears to move from west to east instead of the normal east to west.
How does this affect people personally? It doesn't. Unless you're a planetary scientist working on the MESSENGER mission or observing Mercury via telescope, the movements of this planet - or those of any other planet besides Earth - do not affect you one bit. This is because astrology is bunk.