A compound sentence is one that contains two or more related independent clauses (or complete sentences), and they are most often connected with a conjunction word like "and" or "but" (which is preceded by a comma) or a semicolon. (The first sentence above is actually an example of a compound sentence, connected with a comma and the conjunction "and.")
One example of a compound sentence in the play is spoken by Lord Capulet in Act 1, scene 2, when he is conversing with the County Paris about Paris's desire to marry Juliet. Lord Capulet says,
But Montague is bound as well as I,
In penalty alike, and 'tis not hard, I think,
For men as old as we to keep the peace (1.2.1-3).
The first independent clause reads, "But Montague is bound as well as I, / In penalty alike," followed by a comma and then the conjunction "and." The second independent clause reads, "'tis not hard, I think, / For men as old as we to keep the peace."
Another example, from this same scene, is likewise spoken by Lord Capulet. He says,
But woo her, gentle Paris, get her heart;
My will to her consent is but a part (1.2.16-17).
The first independent clause precedes the semicolon on line 16, and the second independent clause follows the semicolon on line 17.