Learn Romanian: Dar ea nu este bine acum.

To make a sentence negative in Romanian, you simply put the word nu directly in front of the verb. Here, nu goes right before the verb este to mean "is not".

Could I drop the word ea (she) and just say "Dar nu este bine acum"?

Yes! In Romanian, the verb form usually tells you who is doing the action, so subject pronouns like ea are often dropped. Using it here just adds a little emphasis, like pointing out that she is not well, even if someone else might be.

Why is the word bine (well) used here instead of bună (good)?

This is just like the difference between "well" and "good" in English. When talking about someone's health, feelings, or how a situation is going, Romanian uses the word bine (well). If you used bună, it would describe her personality, meaning she is a "good" person.

Can I use a shorter word for este?

Yes, in everyday spoken Romanian, you will very often hear este shortened to e. Saying Dar ea nu e bine acum is extremely common, slightly more casual, and means the exact same thing.