1. It's up in the air: Meaning something is uncertain or undecided.
* Example: "Our vacation plans are still *esta en el aire*." (Our vacation plans are still up in the air.)
2. There's a feeling/vibe: Meaning a certain mood or atmosphere is present.
* Example: "There's a sense of excitement *esta en el aire*." (There's a sense of excitement in the air.)
3. It's a rumor: Meaning something is being whispered about or discussed.
* Example: "There's a rumor *esta en el aire* about a new restaurant opening." (There's a rumor in the air about a new restaurant opening.)
To understand the exact meaning, you need to consider the context of the sentence.