Translation:The woman moves over to sit next to the boss on the sofa.
Moves from one sitting position to another sitting position, close to the boss. The boss says "Come sit beside me" and the woman does so.
Again, the preverb "át-" is indicating a movement from one place to another, similar to "over". And "ül" will be the ending position once the movement is completed. It is implied that the starting position is the same as the ending one. From sitting to sitting. If it were not so, then we would use "oda-":
"A nő odaül a főnökhöz a kanapéra." - The woman was standing until now, and now she goes to the sofa and sits down next to the boss.
"A nő ÁTül a főnökhöz a kanapéra." - The woman was sitting somewhere until now, and now she goes to the sofa and sits next to the boss.
This is fascinating. The Hungarian sentence conveys so much information in so few words. In English it would have to be something like '...changes her seat to one next to...'
An invented phrase like 'sits over to' does seem like a better way to remember how the Hungarian works.
One more interesting example: To join some group, like a team, can be expressed with "beáll":
"Beállok a csapatba" - I join the team
And if I change teams, join the other (possibly opposing) team:
"Átállok a másik csapatba" - I leave this team and join the other team.
I successfully wrote this awkward English sentence almost exactly as they expected it, but it was marked wrong because I said "couch" instead of "sofa"??
There might be a difference between a kanapé and a heverő, but I can assure you that there is no difference between a couch and a sofa. (Yes, I will report it.)