"The priest shall then take the basket (with the first fruit) from your hand and place it before the altar of God your Lord."
The mitzvah of the first fruit contains in it the secret of the return of the lights of the Female to kindness - represented by the Kohen - so that evil forces cannot cling to her. The gematria of הטנא - the basket - is the same as אדני - My Master, the name of God.
Rabbeinu Bechai explains this further. The first fruit remind us of God, who is First, and of the first three letters in God's name giving power to the fourth one. The Kohen taking the basket and waving it is symbolic of God setting the world in motion, for God is also called Kohen. The world is created for the sake of two "firsts" - Torah (which is called the beginning of His way) and Israel (called the beginning of God's harvest). In the same way, the basket is a container serving to receive the first fruit.
Furthermore, God not only directs the world from the outside, while being removed from it, but also penetrates every aspect of the world. The hint to this is in the basket being made of twigs, with a number of holes in between. God is described in the Song of Songs as "peering through the lattices."
Art: Dante Gabriel Rossetti - Girl At A Lattice