We use the second conditional (also sometimes called the "present unreal conditional") to talk about a situation that is not real or is unlikely to occur and its imagined consequences. For example, I might say, "If I had a million dollars, I would go on a trip around the world." I don't have a million dollars. That situation is unreal. But if I did have a million dollars, the consequence would be that I would go on an around-the-world trip.
The second conditional is formed with two clauses. The first clause consists of If + subject + past tense verb, as in, "If I loved her." The second clause is formed with "subject + would + verb," as in, "I would marry her." So, all together, the sentence looks like this: "If I loved her, I would marry her."
Second Conditional Grammar Quiz
Second Conditional Lessons: