It's a common exclamation used to express:
* Surprise: Similar to "Oh my goodness!" or "Wow!"
* Joy: Like "Oh happy day!" or "I'm so thrilled!"
* Sadness: As in "Oh dear" or "Oh no!"
It's an affectionate and versatile phrase that can convey a wide range of emotions.
Keep in mind that the actual meaning of "ya Einy" can depend on the context and the speaker's tone of voice.