Caesura is a pause for a beat in the rhythm of a verse, often indicated by a line break or by punctuation.
From A Poet’s Glossary
The following additional definition of the term caesura is reprinted from A Poet's Glossary by Edward Hirsch.
From the Latin caedere, meaning “to cut”; a pause in the poetic line. The caesura comes at the end of a unit of sense and is signaled either by a comma or a period. It is marked in scansion by a double vertical line (||). For example, there is a caesura after the semicolon in the first line and after the comma in the second line of this sonnet [“The World Is Too Much With Us”] by William Wordsworth (ca. 1802):
The world is too much with us; || late and soon,
Getting and spending, || we lay waste our powers
See also meter.