I hear that the term "landlord" is used mostly for male. But is it also used for female? If not, what is a better word for expressing female owner?
While you can certainly use the feminine form "landlady" if you want to be specific about their gender, this is an example of a word that's generally used regardless of the person's gender, that is to say, "landlord" no longer implies "male landowner". From Wikipedia:
A landlord is the owner of a house, apartment, condominium, land or real estate which is rented or leased to an individual or business, who is called a tenant (also a lessee or renter). When a juristic person is in this position, the term landlord is used. Other terms include lessor and owner. The term landlady may be used for women owners, and lessor applies to both genders.
Men and women can both be landlords, although you can also call a female landlord a landlady. The concept of a landlord goes back to feudalism — the lord part comes from "Lord of the Manor."