What is the meaning of the phrase "وقد يكون المرجع متأخراً لفظاً لا رتبة كقوله : (فأوجس في نفسه خيفة موسى)" and what is the meaning of the word "رتبة" in it?

The meaning of the phrase "a pronoun may refer to something that comes later in wording, but not in rank" is that a pronoun may refer to a word that comes after it in the verbal order, but this word precedes it in importance or grammatical rank. An example of this is the Almighty's saying: "So he conceived in himself a fear—Moses" (فَأَوْجَسَ فِي نَفْسِهِ خِيفَةً مُوسَى). The pronoun in "himself" (نفسه) refers to "Moses" (موسى), who came later in wording, but precedes it in rank because he is the doer (fa'il).