Hi Brother Luka:
A humble and quiet spirit?
I think several good responses have already been given, but to confirm more than add...
A humble and quiet spirit in a man is not the Alpha Male, take-charge-man. It is a man whom knows a man's flesh in-charge is not seeking God's glory but something of his own glory. Therefore his leadership, insights, opinions are directed by the guiding of the Holy Spirit. Humility waits upon God, the flesh has it own ideas and methods pre-packaged and needs no prayer or guidance from God's Spirit in order to act.
A quiet spirit, is as I understand it is not talking about silence...although that might be required in many circumstances. A quiet spirit is a meek spirit, bridled. A very strong spiritual man is strong as a result of proven and experienced interactions with God and man where he has begun to understand surly attitudes, harshness, rage or belligerence toward others worketh not righteousness in himself or others.
Being at peace, and knowing to pursue peace within oneself and in other matters creates a willingness in open hearts.
Unhurried confidence in a very present Lord, a rest in God demonstrates a humble and quiet spirit.
A quiet spirit in the face of liars, detractors, persecutors, accusers, haters...all of this Jesus stood silent, not because he had nothing to say, but had nothing to say at that moment, God guiding him and portraying godliness to everyone of his accusers.
No defense was to be made at that moment, His Father defended him...not by delivering him from his cup, but from anyone saying what he did he did for himself. A humble spirit is nailed to a cross, listening to falsehoods, false accusers, weak and ungodly men whom he knew God's wrath was only a few absent breaths from their bodies.
So much to be said, and there are others here who can say it far better and show it far better than I.