# you are sons

"you are his children". In Paul's culture, inheritance usually passed to male children. He was not excluding female children here. 

# who cries

The Spirit is the one who cries.

# Abba

This is the way a young child would address his father in Paul's home language, but not in the language of the Galatian readers. To keep the sense of a foreign language, translate this as a word that sounds as much like "Abba" as your language allows.