Can you explain this quote of Priscilla on spiritual warfare ?

Of course. The invisible world is the world of ideas. So for example, you are hungry and a cookie belonging to someone else is sitting on the table. Do you grab the cookie and satisfy your hunger, or just stay hungry, since grabbing the cookie would be stealing? It a struggle in the invisible world of ideas, which is directly connected to the visible world. 

Satan is acting evils at us , human being , in the hidden world that can not be seen by our materialistic or concrete and  abstract world , but GOD inform us that satan is our arch and open enemy , who try its worse to snare and deceive mankind to hell with him. So while we , as human being , are having wrestling match with satan in the invisible and spiritual world , GOD advice us to pray for HIM and ask HIM to protect ourselves from the evils of the damn satan and also pray that ,May GOD bestows upon us the goodness of this world and the goodness in the hereafter world and forbid us from the burning of the tormented hell fire.But remember satan is running in ourselves , as if the blood is running in our veins. 

The invisible spiritual world exists only in the fertile imaginations of superstitious folks...

There's a bunch of imaginary entities always fighting with each other.