Translation:The famous actresses get into the taxi.
I agree, but maybe the idea is to learn to think as they do in Hungarian. In Hungarian you can "sit into" something.
Again I don't understand : IN the taxi seems to me A TAXIBAN,that is without a movement
Then it means there is no movement into so that a taxiban would seem more natural
No, "beülnek" signifies motion into (from outside the taxi into the taxi), while "is sitting in" is a non-moving position (already inside the taxi).
I partially disagree.
The famous actresses are sitting in the taxi.
This signifies "motion into"as well. It is determined at the time when said.
In English "they are sitting in the taxi" doesn't imply motion; it indicates location. You'd have to say they "are getting in/into the taxi" to get the same meaning as the Hungarian sentence. "Sitting" isn't a motion verb in English. The closest would be "sitting down" ("they are sitting down" can signify movement), but that can't be used with "taxi."
"Beülnek" means they're in the process of getting into a taxi. "Are sitting in the taxi" means they've already gotten in; they're sitting (seated). The English present progressive unfortunately does not imply motion in this case; it just means that the event is currently happening (they are sitting in the taxi right now). It's not the same thing as the Hungarian "beülnek."