For explanation see E.N.'s 5, 6 and 9 of Surah Hajj (XXIl).
Now let the disbelievers consider the Message of the Holy Prophet by observing their own creation, for this will convince them of its truth by proving its doctrine of Tauhid. The origin of man is from a mere inanimate sperm-drop, which undergoes several changes in the womb of the mother. But after this, when it sees the light of the day, it is quite a different creation from the embryo in the womb. Now it can hear, it can see, and in due course of time it can talk and think. Then, when he reaches adulthood and maturity, he is capable of performing wonderful deeds. It is obvious that Allah alone could create all these characteristics in an inanimate sperm-drop.
The various stages of the creation of man have been cited to prove that Allah is All-Blessed and there is no human language which can describe the praise of which He is worthy, as if to say, "That Allah Who is able to develop an essence of clay into a perfect man, does not have any partner in His Godhead. Moreover, He has the power to raise him up again after his death, and is capable of working even greater wonders.