According to Dr Sharib:-

"Al-Khabir is the One Who knows well and is fully acquainted with the
intricacies and the implications of the universe and the One from Whom
nothing is hidden."
He says emulation of the name requires that one acquaint oneself well
with one's own inner kingdom - the kindom of the heart, mind and body.
One should save oneself from the pernicious influences besetting life,
renouncing the hidden evils in the heart, such as jealousy, malice, greed,
dishonesty, lust, cunning, craftiness and hypocrisy. One should refrain
from following those dictates of the heart which lead one astray.

Appropriate recitation can help in revealing the hidden secrets and can
secure deliverance if you are entangled in the net of an undesireable

see 'The 99 Most Beautiful Names of Allah' by Dr Zahurul Hassan Sharib

Some other references:

Al-Ghazali says: '(Al-Khabir) has the same meaning as 'Omniscient', yet
when knowledge ['ilm] is related to hidden secrets it is called awareness
[khibra], and the one who possesses it is 'He who is aware [of everything]'.

(Al-Ghazali - The Ninety-nine Beautiful Names of God. Trans. Burrel/Daher: ITS: 1992.)

One of the innumerable and great kindnesses of God is when the spiritual
guide enables one travelling on the sufi way to become aware of his/her
inner kingdom. From this it becomes possible to understand that one has
to manage one's own inner world as a vice-regent, developing its
'ecology' to ensure that all parts work together harmoniously. Each part
benefitting other parts and all working together for the whole. I remember
Zahurmian emphasising the team work required between the different
elements. In modern parlance we may talk about it as effecting a synergy.

Bismillah ir Rehman ir Rahim
The Well-informed, The Aware, The All-Cognisant One,
The Knowing, The Cognisant, The Totally Aware
Qur'an 6:18
He is the Irresistible, (watching)
From above over His worshippers:
And He is the Wise,
Acquainted with all things.
Wa Huwal-Qaahiru fawqa
'ibaadih: wa

(Qur'an 6:18 trans. Y. Ali)