Here, Christ says that the "poor in spirit" - those who recognize their own spiritual poverty - will have "the kingdom of Heaven." But in Matthew 5:5, Christ says that the meek will inherit the earth. Are the meek Christians going to have a different reward from the "poor in spirit" Christians? Is this a contradiction? Of course not! The "meek" and the "poor in spirit" - in other words, humble Christians - shall inherit the earth for an everlasting possession, and shall enter the "Kingdom of [owned by] heaven" which will be set up on earth! That Kingdom is the divine, ruling government of God which Christ will establish on earth at His return (Revelation 5:10).
To enter into - or "inherit" - the divine Kingdom of God is a destiny of such marvelous glory that the human mind cannot fully grasp it! Men today have no conception of what is in store for the obedient. The inheritance that awaits every true Christian surpasses anything we have ever conceived in our minds!
As we read in I Corinthians 2:9, "Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him." The full extent of the inheritance God has promised the righteous cannot even be remotely imagined by the natural mind of man - but God does reveal it to us "by His Spirit" (verse 10).