“VATICAN CITY, June 23 (Reuters) - The Vatican on Tuesday reaffirmed a long-standing rule that only an ordained priest or deacon can give a sermon at a Catholic mass, rejecting a request from German bishops to broaden the practice and allow sermons by women or other laypeople.”
Let me spell it out
the most common way to become a Priest is through a religious order
When in formation, you decide to be a Brother or a Priest if you are in a male order
and in a female order, you are a nun after formation
some become Brothers and not priests as they want to support the Order and have more time to dedicate to Theology, Writing, Reading, etc.
you just cannot be ordained into the Priesthood as a woman