An end-stopped line is a line of poetry that ends at a natural pause, usually with punctuation or the end of a complete thought. The line feels finished before the next line begins, which can slow the pace and give the reader a brief stop. It is the opposite of enjambment, where the thought runs on into the next line.
Example
The evening folded softly over the hill.
The garden went quiet.
One window still glowed warm.