Questions & Answers about Я купила маленькую сумочку к светлой блузке.
Because the speaker is female.
In the past tense, Russian verbs agree with the subject in gender and number:
- купил = he bought / I bought if the speaker is male
- купила = she bought / I bought if the speaker is female
- купило = neuter
- купили = plural
So Я купила tells us that the person saying this is a woman.
Because it is the direct object of the verb купила, so it has to be in the accusative case.
The dictionary form is:
- сумочка = handbag, little bag
But after купить (to buy), we ask what did she buy? The answer is the object, so we use the accusative:
- сумочка → сумочку
This is a very common pattern for feminine nouns ending in -а / -я:
- книга → книгу
- машина → машину
- сумочка → сумочку