The prologue to Romeo and Juliet is a Shakespearean sonnet of fourteen lines written in iambic pentameter, and divided into four subgroups.
The first three subgroups are stanzas called "quatrains," which consist of four lines each. In a Shakespearean sonnet, the rhyme scheme of these three quatrains is ABAB (dignity/mutiny, scene/unclean), CDCD (foes/overthroes, life/strife), and EFEF (love/remove, rage/stage).
"Love/remove" is a bit of a stretch for us, rhyme-wise, but if it was good enough for Shakespeare, it should be good enough for us. During Shakespeare's time, "love" and "remove" might have rhymed—"loov" and "re-moov" seem the most likely rhyming possibility—but scholars are still debating the issue.
The fourth subgroup is a two-line "rhyming couplet," with a GG rhyme scheme (attend/mend).
The prologue is a brief summary of the play, which is intended to raise the audience's interest, quiet them down, and draw them into the "world of the play."
The first quatrain sets the scene of the play, "in fair Verona," and establishes the major characters, "two houses both alike in dignity." It also describes the basis of the overall conflict between the two dignified houses, "from ancient grudge," and explains the situation between the two dignified houses at the beginning of the play, "break to new mutiny."
The second quatrain describes the plight of the "star-crossed lovers" which arose out of the conflict between the two families. It hints at the lovers' unfortunate lives, "misadventur'd piteous overthroes," and provides a major spoiler by revealing the lovers' deaths as a result of their misadventures.
The third quatrain describes the primary focus of the play, "the two hours’ traffic of our stage," as the course of the lovers' lives, "The fearful passage of their death-mark'd love," which occurs within the continuing conflict between the two families, "the continuance of their parents’ rage."
These three quatrains tell the audience everything they need to know to understand the play and get them involved in the story, but the fourth part of the sonnet, the rhyming couplet at the end of the sonnet, actually has nothing to do with the brief introduction to the play.
The chorus is saying to the audience, if you will listen quietly and patiently to the performance, "if you with patient ears attend"—Elizabethans went to "hear" a play, not to "watch" a play, and they were sometimes an unruly crowd—you'll hear (and see) much more than I could tell you about in this short prologue, "What here shall miss, our toil shall strive to mend."
In other words, the chorus was saying, "sit back, relax, don't throw things at the actors, and enjoy the show"—or "stand back, relax, don't throws things at the actors, and enjoy the show," for the many audience members who were standing in the "pit" or "yard," which was the low-priced, "standing room" area in front of the stage.