# For you were slaughtered

"For they slaughtered you" or "For people killed you" 

# slaughtered

If your language has a word for killing an animal for a sacrifice, consider using it here.

# with your blood

Since blood represents a person's life, losing the blood represents dying. This probably means "by your death" or "by dying." 

# you purchased people for God

"you bought people so that they could belong to God" or "you paid the price so that people could belong to God"

# from every tribe, language, people, and nation

This means that people from every ethnic group are included.