Heroic couplets are rhyming pairs of verse in iambic pentameter.
What on earth did these couplets do to become heroic? Did they pull a cat out of a tree or save an old lady from a burning building? In fact, no.
They're called heroic because in the old days of English poetry they were used to talk about the trials and adventures of heroes. Heroic couplets totally ruled the poetry scene for a long time, especially in the 17th and 18th centuries, when a dude named Alexander Pope was rocking the neoclassical world with works like "Sound and Sense," which just so happens to be written in heroic couplets.