# Hosanna

This word means "save us," but it can also mean "praise God!"

# the son of David

This may be translated as "descendant of king David." However, "Son of David" is also a title for the Messiah, and the crowd was probably calling Jesus by this title.

# in the name of the Lord

"in the power of the Lord" or "as the representative of the Lord" 

# Hosanna in the highest

"Praise God, who is in the highest heaven" or "Praise be to God"