Questions & Answers about Моя соседка жалуется, что в комнате душно.
Because соседка is a feminine noun, and the possessive my must agree with it in gender, number, and case.
- мой = masculine singular
- моя = feminine singular
- моё = neuter singular
- мои = plural
So:
- мой сосед = my male neighbor
- моя соседка = my female neighbor
Соседка means female neighbor.
Сосед means male neighbor or sometimes neighbor in a general masculine form.
Russian often distinguishes male and female people with different noun forms:
- сосед = male neighbor
- соседка = female neighbor
The ending -ка here helps form the feminine version.