" Instead, be concerned above everything else with the Kingdom of God and with what he requires of you, and he will provide you with all these other things." (Matthew 6.33)

What is the real meaning of this sentence ?

Priorities. Spiritual first, which relates to our eternal condition, followed by material, which God promises to provide if our priorities are right.

Good answer Galveston. That's absolutely it in a nut shell.

It would help a little to go back a couple verses, pmh.

Matthew 6:31, 32, 33 "Therefore take no thought, saying, What shall we eat? or, What shall we drink? or, Wherewithal shall we be clothed? For after all these things do the Gentiles seek: for your heavenly Father knoweth that ye have need of all these things. But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you."

Because we are in this world, in this flesh, it is so much easier for us to concern ourselves with our flesh. It is harder though, for us to put our spiritual self first, but that is what God wants us to do because this flesh will end. He is saying in these verses that God knows what our needs are. If we put God first in our lives, He will take care of our fleshly needs.

I see from your questions that you are searching for answers. Go to the One who can answer them for you. Find the real relationship with Jesus and His Holy Spirit will guide you into all Truth. Therein you will find the answers you seek.