What is your zodiac sign if you are born on 28th January?

Between February 21 and March 21 (dates vary slightly from year to year) the sun is said to be in the sign of Pisces, so your sun-sign is Pisces.
If you are interested in Astrology you might also want to find out the signs of the moon, the other planets and the rising sign, but these need to be calculated specially for you and ideally need your time and place of birth as well. Check a web-site like astro.com.