Another special mitzvah of Sukkot is the shaking together of the
"Four Species" -- the etrog (citron), lulav (palm branch), three
hadassim (myrtle branches), and two arovot (willow branches).
Each day of Sukkot (except the Sabbath), we shake the "four kinds"
during the daytime.
Hold the lulav, hadassim, and arovot in the right hand, with the
lulav's "spine' "facing you.
Say the appropriate blessing(s), then take the etrog in the left hand
with the point, or "pitom," up, bring it together with the other
three kinds, and shake it.
One explanation, among many, is that each of the four kinds
represents a different type of Jew.
The fact that the mitzvah requires all four kinds symbolizes our
oneness as a people: we all need one another. And the four species
are waved in all four directions, and up and down, signifying that
G-d is everywhere.