A unit of language into which a poem
or play is divided is called a... *

Answer + Explanation:

A line is a unit of language into which a poem or play is divided, which operates on principles which are distinct from and not necessarily coincident with grammatical structures, such as the sentence or single clauses in sentences.

Stanza

Explanation:  A line is a unit of language into which a poem or play is divided, which operates on principles which are distinct from and not necessarily coincident with grammatical structures, such as the sentence or single clauses in sentences. ... A distinct numbered group of lines in verse is normally called a stanza.

dr. kings dream speech

explanation:

it was late in the day and hot, and after a long march and an afternoon of speeches about federal legislation, unemployment and racial and social justice, the rev. dr. martin luther king jr. finally stepped to the lectern, in front of the lincoln memorial, to address the crowd of 250,000 gathered on the national mall.