When we gassho we manifest the body karma of the three virtues. It is nearly impossible to communicate the meaning of this in words. Most of it is a process of personal discovery. If you just sit cross-legged and make the cosmic mudra with your hands, you may appreciate how that mudra affects your whole being, how it can turn your attention inward to the deepest aspects of yourself. There are other mudras, some that turn you outward, toward the world, but all of them are about the karma of body.
Words are also karma.
What we say has a tremendous impact on our lives and on the world around us. When we vow to attain the Way, we connect with the karma of that vow. In chanting the name of the Buddha, we are one with the Buddha. There is no separation. When our words are motivated by compassion and wisdom, they manifest as wisdom and compassion.