And verily, it is in the Mother of the Book with Us, indeed exalted, full of wisdom.
This explains the high status of the Qur'an among the hosts on high (the angels), so that the people of the earth will respect it, venerate it, and obey it.
وَإِنَّهُ (And verily, it),
means, the Qur'an,
فِي أُمِّ الْكِتَاب (Is in the Mother of the Book),
meaning, Al-Lawh Al-Mahfuz (the Preserved Tablet).