Literal meaning: to rearrange the structure of something.
Real meaning: to sack lots of workers.
A euphemism used by bosses to cover up the fact that they're planning to sack workers or to attack workers in other ways (e.g. worsen pay and conditions).
Boss: We're planning a major restructuring of this factory.
Union rep: erm - what's that?
Me: It means they're going to sack loads of people, you idiot! Quick, do something!