Singing with Understanding

Isn't is great when you've read a passage dozens of times, and then you notice a new aspect of it?

Sing praises to God, sing praises!
Sing praises to our King, sing praises!
For God is the King of all the earth;
Sing praises with understanding.
- Psalm 47:6-7 (emphasis added)

We are told to sing. But don't just sing meaningless words. Sing with understanding.