The <em>converse</em> of a statement is one in which<em> its hypothesis and conclusion are reversed. </em>A statement of the form p⇒q (p implies q) becomes the statement q⇒p (q implies p).
Here, if we let p be the statement "planes are parallel" and let q be the statement "they do not intersect," then q⇒p would be "If planes do not intersect, then they are parallel."