Psalms 133

1 It is very good and very pleasant for God’s people to gather together harmoniously.

A song for pilgrims going up to Jerusalem. A psalm of David. How good, how delightful it is when people live together lin harmony!

2 It is [as delightful as] the precious/expensive ([olive] oil/perfume) that runs down from [the Supreme Priest] Aaron’s head onto his beard [when he is anointed] and runs down onto the collar of his robes.

This is as precious as the oil used to anoint Aaron, running down from his head onto his beard, onto the collar of his clothes.

3 Gathering together harmoniously [is as delightful] as the dew [that falls] on Hermon [Mountain] and the dew that falls on the hills near Zion [Hill]. Yahweh has promised to bless [his people there in Jerusalem] [by giving them] everlasting (OR, a long-lasting) life.

It's like the dew of Mount Hermon that falls on Zion's mountains. That is where the Lord gave his blessing of life that lasts forever.