Psalm 2:12. "Kiss the Son, lest He be angry, And you perish in the way, When His wrath is kindled but a little. Blessed are all those who put their trust in Him".
The second part of this verse explains what the first part means. Thus "To kiss the son", means 'to put ones trust in him".
This verse is a prophetic verse, pointing to the importance of putting ones trust in Jesus.
Prophetic verses does not need to have contemporary context, although this verse could have derived from some pagan worship, with the promised future messiah, the "Son", replacing the name of a contemporary pagan deity.
Christmas and Easter have been claimed to be Christenized pagan holidays. The former substituting worship of the Roman sun-God 'Sol Invictus', and the latter worship of the old English deity Ēostre.