Having perfect peace is to be grounded in the Lord and His love. You have no worries and all your trust, faith, and hope is in Him. You know that God will provide for you no matter what the circumstances.
(Isaiah 26: 2-4) 2 Open the gates,
That the righteous nation which keeps the truth may enter in.
3 You will keep him in perfect peace,
Whose mind is stayed on You,
Because he trusts in You.
4 Trust in the Lord forever,
For in YAH, the Lord, is everlasting strength.