# This will be a reminder for you on your hand, and a reminder on your forehead

These are two different types of physical reminders so people will not forget something important.

# a reminder for you on your hand

"like something you tie around your hand as a reminder" 

# a reminder on your forehead

"like something you tie around your head as a reminder"

# so the law of Yahweh may be in your mouth

"so you may always be speaking of the law of Yahweh"

# strong hand

"the power I show in my works"