You should set this subject aside and concentrate on other areas of English writing. Appositives, compound possessives, em dashes, Oxford commas -- these are all advanced subjects which should be studied only after completely mastering the many more-common grammar issues that give learners trouble.
I do not have any trouble with any gramamatical terms and even though I do not have trouble with appositives. I have a doubt only on these patterns.
Pattern 6: An introductory series of appositives followed by a dash, a summarizing word that may be the subject, and a verb.
Examples: Vanity, greed, corruption—which serves as the novel’s source of conflict?
Bull riding, camel races, bronco riding, and roping—these events mean “rodeo” to many people.
The Mona Lisa, Michelangelo’s David, the frescoes in the Sistine Chapel—many are the wonders of the Renaissance in Italy.
Pattern 7:An internal series of appositives or modifiers enclosed by a pair of dashes or parentheses.
Examples:The necessary qualities for political life—guile, ruthlessness, and garrulity he has learned from his father.
The much-despised predators—mountain lions, timber wolves, and grizzly bears—have been shot trapped, and poisoned so relentlessly for so long that they have nearly vanished from their old haunts.
The basic fencing moves (the advance, the retreat, the lunge) demand careful balance by both fencers.