новой

новой

"New" (feminine form).

In this sentence, 'новой' ('new') is declined in the accusative case to match the feminine noun 'машину' ('car').

Я купил новую машину.

I bought a new car.

'Новей' appears in the instrumental case, corresponding to the feminine singular noun 'соседкой' ('neighbor').

Мы познакомились с новой соседкой.

We got acquainted with the new neighbor.

Here, 'новой' is in the prepositional case, agreeing with the feminine singular noun 'книге' ('book').

В новой книге много интересных историй.

In the new book, there are many interesting stories.