This is nothing new. The effects of precession have been well known for thousands of years.
Short version, as viewed from Earth the Sun crosses 13 constellations over the course of a year. Whatever constellation the Sun was in at the time of your birth is your "sign." The Earth wobbles on its axis, so the dates the Sun is in these constellations is constantly changing. Each cycle is 26000 years. Also, each constellation is of a different size and the Sun's path through them isn't equal so the number of days the Sun spends in each constellation varies with each one, from a high 45 days in Virgo to a low of 7 days in Scorpius. Currently the Sun is in Virgo, and will be through October 30th. The current "age" is the constellation in which the Sun is in at the time of the vernal equinox. Currently, that would be in the Age of Pisces, which has been the case since 67 BC. We will move into the Age of Aquarius in 2597.
Of course, none of that really means anything and astrology is just a bunch of crap anyways, other than as a source of entertainment.