Final answer:
The phrase 'prevent sb from doing sth' means to stop someone from doing something.
Step-by-step explanation:
The phrase 'prevent sb from doing sth' means to stop someone from doing something. It is used to describe the action of hindering or obstructing someone from carrying out a particular activity or action. For example, if someone is prevented from publishing a book they plan to release, it means they are stopped or prohibited from doing so.