What does it mean that "Allah is exalted above time and space"?

That Allah is exalted above time and space means that His existence is in no way limited by time or space. This is because time and space are created—they are "creatures." Allah, on the other hand, is the Creator. Therefore, He is free from, that is, far removed from, the characteristics specific to created things. To elaborate further, created beings exist within a certain time and space. Time is the measurement of movement within beings and is not something separate from existence itself. Ultimately, it too is created. Allah, however, is the One who brings everything into existence. (el-En‘âm, 6/102) "He is the Creator of the heavens and the earth..." (Fâtır, 35/1) Therefore, Allah is beyond all kinds of limitations of time and space.

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu