Psalms 133

1 A Song of Ascents. David’s. Lo! how good and how delightful, for brethren, to dwell together even as one.

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 Like the precious oil upon the head, descending upon the beard; the beard of Aaron, —which descended unto the opening of his robe:

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 Like the dew of Hermon, which descended upon the mountains of Zion, —for, there, did Yahweh command the blessing, Life, unto times age-abiding?

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.