# in these last days

"in these final days." (Deuteronomy 4:30). This phrase refers to the time when Jesus began his ministry, extending until God establishes his complete rule in his creation.

# through a Son

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

# to be the heir of all things

"to possess all things" 

# It is through him that God also made the universe

"It is through the Son that God also made all things"