Family terms: whose family?
Japanese family terms depend not just on the relationship, but on whose family you mean and whom you are addressing. Separate descriptions to outsiders from direct forms of address at home.
Describe your own family
When describing your parents to someone outside the family, 父（ちち） and 母（はは） are basic choices. 父は会社員です。 means 'My father is a company employee.' A polite sentence does not require changing 父 to お父さん.
For your own siblings, use 兄（あに） for an older brother, 姉（あね） for an older sister, 弟（おとうと） for a younger brother, and 妹（いもうと） for a younger sister. Unlike the Korean terms for older siblings, 兄 and 姉 do not change with the speaker's gender.
Other people's family and direct address
For another person's parents, お父さん and お母さん are common choices. ご両親 is a respectful term for parents. Identify whose parents are meant before choosing the expression.
Within a family, people address parents as お父さん, お母さん, or other household-specific names. Although 父 refers to one's own father, that does not mean it is the usual word to call out when addressing him.
Avoid mechanical substitutions
Friends sometimes use forms such as お母さん when talking about their own family. Rather than treating that as wrong in every context, start by learning the basic pattern for politely describing family to an outsider.
Some people may not have or may not wish to discuss a particular family relationship. Do not demand an answer in conversation practice; describe only known relationships. Knowledge of family terms is not a basis for guessing personal information.
Check: How can you politely tell someone outside your family that your mother is a teacher?
Show the answer and why
You can say 母は教師です。 It combines 母 for describing your own mother with polite です, rather than using a direct form of address.