وَجَدتُّهَا وَقَوْمَهَا يَسْجُدُونَ لِلشَّمْسِ
I have found her and her people prostrating to the sun - 27:24
This shows that her people were star-worshippers and used to worship the sun. Some believe that they were Zoroastrians, who worship fire and all forms of light.
أَلَّا يَسْجُدُوا لِلَّـهِ الَّذِي يُخْرِجُ الْخَبْءَ (that is, they do not prostrate to Allah who bring forth what is hidden - 25).This sentence is linked with the previous one, "The Shaitan has beautified their deeds - 26" and the sense is that the Shaitan had engrained in their minds that they should not bow down before Allah, or had prevented them from the righteous path so that they should not prostrate before Allah Ta’ ala.