This means that their horses are only horses and not spiritual beings. Alternate translation: "their horses are only horses; they are not powerful spirits" (See: [[rc://en/ta/man/translate/figs-explicit]])
The term "hand" is often used in reference to God's power and action. Alternate translation: "When Yahweh uses his power against them" (See: [[rc://en/ta/man/translate/figs-metonymy]])
These two phrases mean basically the same thing. Stumbling and falling are metaphors of failing. This can be stated in active form. Alternate translation: "these two things will happen: I will destroy Egypt, who helps you, and I will destroy you, whom Egypt helps" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-parallelism]])