# In the seventh year

"In year 7 of Athaliah's reign" 

# Jehoiada

the high priest

# the commanders of hundreds

"the commanders of 100 soldiers" or "the commanders of military divisions" 

# Carites

This is the name of a particular group of the royal guards.

# brought them to himself

"had them come to meet with him." 

# Then he showed them the king's son

Jehoiada revealed to them that Joash, King Azahiah's son, was still alive.