1.  Say: I seek refuge with the Lord of the Dawn,

The Lord of the Dawn is a title of Allah

2.  From the mischief of created things;

3.  From the mischief of Darkness as it overspreads;

The Darkness is spiritual corruption caused by Greed.

4.  From the mischief of those who practice Secret Arts:

The Secret Arts refer to anything metaphysical.  In this context, it means spiritual power others are using to harm you. 

5.  And from the mischief of the envious one as he practices envy.

This is a plea for help from Allah to keep you safe when others wish you harm.  Those wishing to use this prayer should recite, preferably from memory, all five passages (all the bold print).