Depending on context, "(noun)는" could be translated as either singular or plural, as it is common for 은/는 to imply the sentence to be a general statement.
For example: "자동차는 차량 입니다." could be literally translated as "A car is a vehicle." and gives the same general idea as "Cars are vehicles."
아니다 (아닙니다) isn't used for negating verbs.
이다 describes a thing by equating it with another thing. Ex: I'm a man. -> 저는 남자입니다.
아니다 is the opposite of that. So, I'm not a woman. -> 저는 여자아닙니다.
If you want to negate a verb, there are two general forms you can use:
1) 안 + (verb)
In this example: 안 배웁니다 or 안 배워요.
2) (base form of verb)지 않다
In this example, we could use "배우지 않습니다" or "배우지 않아요".