This returns the western star sign for a date of birth, together with the sign's date range and the neighbouring signs on either side. It is a date lookup and nothing more — a mapping from a calendar date to one of twelve names.
The boundaries are not quite as fixed as the printed tables imply. Each sign begins when the sun reaches a particular point, and that moment shifts by up to a day from year to year, drifting with the leap-year cycle. Births within about twenty-four hours of a boundary — described as being on the cusp — therefore need the year as well as the date to be settled, and a table that gives a single set of dates for all years will occasionally place them wrongly.
The system is the Babylonian and Greek one that reached Europe and from there the rest of the world, and it is worth keeping separate from the two other cycles that circulate widely in the UAE. The Chinese animal cycle, which the separate calculator here covers, runs on a different calendar entirely. The Hijri calendar carries no zodiac of any kind, and its months have no equivalent function.