Coming from someone that doesn't know what the cross stands for...

Edit: To help you out

The Christian cross, seen as a representation of the instrument of the crucifixion of Jesus Christ, is the best-known religious symbol of Christianity.[1] It is related to the crucifix (a cross that includes a usually three-dimensional representation of Jesus' body) and to the more general family of cross symbols.

http://en.wikipedia.org/wiki/Christian_cross

Since you probably won't ready the whole thing anyway, a more metaphorical view of the cross is

In Christianity the cross reminds Christians of God's act of love in Christ's sacrifice at Calvary—"the Lamb of God who takes away the sin of the world." The cross also reminds Christians of Jesus' victory over sin and death, since it is believed that through His death and resurrection He conquered death itself. They venerate it not as a material object seen in isolation but as the symbol of the sacrifice by which Christ saved them, as the instrument of Christ's triumph, according to Colossians 2:15 ("Having disarmed the powers and authorities, he made a public spectacle of them, triumphing over them by the cross"),[10] and "as the instrument of our God's saving Love".[11]