Answer:
A line break is the termination of one line of poetry, and the beginning of a new line.
Some additional key details about line breaks:
Line breaks divide poems into lines, and the length of lines determines the appearance of the poem on the page: long and skinny, short and wide, or a shape entirely its own.
The location of a line break is often dictated by the number of syllables in the line, but just as often it is freely chosen by the poet.
Line breaks serve an important function in setting the rhythm of a poem, since they insert a pause between the final word of one line and the first word of the next line. For this reason, line breaks conventionally occur where natural pauses in language also occur—such as after punctuation, at the end of a thought, or between distinct images.