Translation:Éva and her friends are not studying, but playing.
You don't really know. This "Éváék" thing is really hard to translate to English, but we use it only if it's obvious from the context who we are talking about. Literally it means something like "Éva and her company", or "Éva and the people around her". This sentence would be realistic in a situation when, for example, Éva tells her parents that she's going to study at her friends', but someone tells the parents that they're not studying, but playing.
Theoretically, yes, it could be. But it is usually a specific group of people (who belong together, or just happen to be together at the moment), not a generic one describing all who might be together. For example, you know that some people you invited to your party will come together, and one of them is Death. Then you get a phone call and learn that "Halálék" cannot come because their car broke down.
You can also use it to describe a family. "Kovácsék laknak itt." - "The Kovács family lives here."
Just to give people an example: I recently stayed with a lovely Transylvanian family, along with my boyfriend Hugh, who has known them for years.
When speaking about us to each other, they referred to us constantly as "a Hughék" (are the Hughék coming with us, are the Hughék having dinner here today, say goodbye to the Hughék, why do the Hughék have to go? etc.)