Learn Dutch: Mijn oma breit niet meer. - My grandmother does not knit anymore.

We use niet meer because we are negating the verb breit (knits) and the general action of knitting. You would use geen ... meer when negating an unspecific noun, for example: Mijn oma breit geen truien meer (My grandmother doesn't knit sweaters anymore).

Why is niet meer placed at the very end of the sentence?

When you negate an entire sentence or the main verb, niet generally moves to the end of a simple main clause. The word meer (anymore) is locked to it here, directly following niet to form the fixed phrase.

Why isn't there a translation for the English word "does" in this sentence?

Unlike English, Dutch doesn't use a "dummy" verb like "to do" to make negative sentences. Instead of saying "does not knit", Dutch simply takes the conjugated main verb (breit) and adds the negation (niet meer).

What is the infinitive of breit, and how is it conjugated here?

The infinitive is breien (to knit). It is a regular verb in the present tense: you take the stem (brei) and add a -t because the subject is mijn oma (a "she" figure), giving you breit.