gap in (someone's) knowledge

Translations
пробел в (чьих-то) знаниях
She has a gap in her knowledge when it comes to ancient history.
У неё пробел в знаниях, когда дело касается древней истории.
Definitions
A lack of information, understanding, or awareness about a particular subject or topic that someone does not know or is unfamiliar with.
Words
gap

noun
разрыв
knowledge

noun
знание