Some translations set each line of poetry farther to the right than the rest of the text to make it easier to read. The ULB does this with the poetry in 15:16.
The Spirit of Yahweh rushed upon Samson. This meant God gave Samson extraordinary strength. Samson's power is the power of Yahweh himself and he enacted the judgment of God on the Philistines. (See: [[rc://en/tw/dict/bible/kt/holyspirit]] and [[rc://en/tw/dict/bible/kt/judge]])