Genesis 11:6

And the Lord said The account, in this and the following verse, is evidently condensed. In Genesis 11:5 Jehovah is represented as coming down on earth, in order to see more closely, and on the spot to form a better judgement. This He has done; He has returned to heaven, and now, in Genesis 11:6, announces what He has seen. In Genesis 11:7 He proposes to descend a second time and inflict punishment.

one people … one language This is evidently contrary to the intention of the Deity who desires the whole earth to be populated.

nothing will be withholden from them i.e. they will be baulked in no enterprise. If they mount up to heaven, their arrogance will make them endeavour to rival God Himself. It is the same kind of apprehension as in Genesis 3:22.