# He is the head

"Jesus Christ, the Son of God, is the head". It is best to translate "Son" with the same word that your language uses to refer to a human son.

# He is the head of the body, the church

Paul speaks of Jesus's position over the church as if he were the head on the human body. As the head rules the body, so does Jesus rule the church. 

# the beginning

"the originating authority." 

# firstborn from among the dead

Jesus is the first person to die and come back to life, never to die again.