In astrology, a bunch of trivia about your life factor into your reading... So like basic newspaper horoscopes are just like "which range of dates does your birthday fall into? Oh okay you're a Pisces then, so go read the horoscope for all Pisces..." But if you go to a "real" astrologer for a "real" reading, they wanna know other stuff, including what time you were born, and that'll help personalize the reading.

Mom is making the assumption that the reason for the question is to use her response as input to an astrology reading. Instead of sharing the time of birth, she warns the subject to stay away from "her," the astrologer, who are stereotypically female.

Short answer: The joke is that astrology girls are crazy.

Context: If you look up your sign according to your date of birth (sun sign) and find that it doesn't fit your personality at all, well you just need to delve deeper, find out your rising sign and moon sign by having a professional (or algorithm) cross reference your time of birth with the fancy astrology chart. Still doesn't fit you? Well you probably just got the time wrong because it has to be to the exact minute. Perhaps it's that your mom doesn't remember correctly, or that many hospitals will fudge the times a little in your birth records. You must work extensively with a professional astrologer, who will assign your sign based on whichever one sounds the most like you. You need the 3 signs for your reading to really "work"

It's astrology stuff lol

it's an astrology girl