This "action" is part of the "kavanah" process. We create a "Dwelling place for the Holy One, blessed be He in the lower realms". This is accomplished through the mitzvot being fulfilled on the level of thought, speech and action. This idea of raising the hands is also repeated in connection with the blessing of the Kohanim, who also raise their hands. It is also performed when you wash before making the blessing of HaMotzi over bread.
Each of the joints of the fingers corresponds to a particular sephirah. Right hand to the side of Chesed. Left hand to the side of Gevurah. When the hands are raised, according to most opinions, they don't get raised above the head. This has an implication that the action is at the point of interface between what is "below" the level of intellect and what is "above" the level of intellect. In particular with the blessing of the Kohanim it is drawing from what is above the level of intellect and drawing this into the world, what is "below intellect".