Based on the level of respect or formality, you can say "This is my mother" in Korean in 3 ways:

• Informal: nae eomma-ya (내 엄마야)
• Formal: jae eomeoni-yeyo (제 어머니예요), jae eomeoni-ipnida (제 어머니입니다)
• Very Formal: jeo-eui eomeonim-isipnida (저의 어머니이십니다)

- this is (introducing someone): ida (이다)
- my: na-eui (나의), jeo-eui (저의), nae (내), je (제)
- mother: eomma(엄마), eomeoni (어머니), eomeonim (어머님)

Please refer to How to pronounce Korean Alphabet for the English pronunciation in this answer.