IC are the first letters of Jesus name in Greek. In traditional iconography the tilde – wavy line over the top – is an ascription of divinity.
XC is a classic greek representation of Christ as the title being God’s anointed and again has the tilde over the top.
NIKA is also greek and the word means Victor. Indeed this is the same word that gave the famous running shoe their name, though I think the Church can claim prior useage.
Surrounding the cross the emblem reminds us that in the death and resurrection of Jesus is our victory over sin and service to self, and our freedom to pursue a yet more excellent way.