What is the meaning of "they prostrate" (yasjudoon) in His (Allah's) saying: "So what is [the matter] with them that they do not believe? And when the Qur'an is recited to them, they do not prostrate"?

"They do not prostrate" has two interpretations: they do not pray, or they do not submit to Allah. The preponderant view is that both meanings are intended, and there is no contradiction between them. For whoever does not pray has not submitted to Allah, and whoever prays has submitted to Him.