This is the 4773rd most frequent Russian word.
запретить
To forbid or prohibit.
Here, "запретить" is used in the context of imposing a prohibition within a specific setting: a classroom rule.
Учитель запретил нам использовать телефоны на уроке.
The teacher prohibited us from using phones during the lesson.
In this sentence, "запретить" refers to a governmental or legal decision establishing a prohibition applicable to society.
Государство решило запретить курение в общественных местах.
The state decided to ban smoking in public places.
Here, "запретить" is used in a familial context where parents establish rules for their child for safety reasons.