Astrology has many meanings in today's world. If you mean by astrology Fortune telling and the claims to foretell a person’s future, then it is not permissible to do so, and any money earned from it is unlawful.
Since the information claimed by the astrologist has no value, it is, therefore, not permissible for him to give information with certainty, just as it is not permissible for the customer to plan any act according to it.
Wassalam