Hands are unique among the body's parts in that, in their default position, they hang downward. However, they have the remarkable ability to be lifted above the head.
This carries deep symbolism. The act of raising our hands represents the potential to accomplish far more than we might imagine. (Hands represent action, as this is where action is performed from, so it represents the ability to accomplish.) as we know that people only use a fraction of their potential. If we put our minds to it, we can accomplish far more than we ever conceived. While we often use only a fraction of our abilities, the act of lifting our hands serves as a reminder that, with focus and determination, we can achieve far more than we thought possible.
Furthermore, the hands’ ability to rise above the head signifies that we must carry out the commands of Hashem that go beyond our intellectual understanding. The hands being raised over the head symbolizes actions above the intellect. That is to say, performing mitzvos we do not grasp with our intellect, such as shaatnez. With this we can grasp ויהי ידיו אמונה, he remained with his hands in faithful prayer, which can be understood to mean to perform mitzvos even if you don’t understand them, because you have emuna in Hashem.
Finally, one last point the hands rising about the head teaches is that merely learning about a mitzva is not enough. It is essential to perform the mitzvah.
