The class is likely to involve you learning at least two formal languages: the language of propositional logic and that of predicate logic (predicate takes everything you already did in propositional, and adds some more things).
You may also spend some time at the start on logic in a natural language, English, looking at things like fallacies.
You will probably need to learn how to translate English sentences into formal sentences, and vice versa. In my experience, this is one of the two things students, including graduate students, have the most trouble with.
You will need to learn how to manipulate symbols in proofs, like:
1. p ^ (q -> ¬p); premise
2. q -> ¬p; 1, ^E
3. p; 1, ^E
4. ¬¬p; 3, DN
5. ¬q; 2, 4, MT
Also, because logic involves proofs, it has something in common with high school geometry classes. You'll spend several weeks on each of these languages, and they won't look nearly as incomprehensible as they do now. The other hardest part of learning all of this is the use of the material conditional (it's like IF-THEN, but it doesn't work the way "if ... then ..." works in English).
You may also learn other things as well, such as functions, set theory, modal logic, etc., but a class called "Elementary Logic" is probably not going to go very far beyond predicate logic.
I suggest that you find out what textbook is being used in Elementary Logic this term (it's probably offered every term) and then take a look at it at the bookstore or on Amazon or Google Books or something. That will give you some idea of what's being taught. Keep in mind that not all professors at your school will necessarily use the same textbook.
If you think you would benefit from getting another logic textbook (hopefully from the library) to help you understand what's in your book and what's discussed in class, I recommend Bonevac's. I haven't read everything that's out there, but Bonevac's is the best of the ones I have read. I also *strongly* recommend the software that comes with the book "Tarski's World." It will generate many practice problems and give you immediate feedback on what you're doing wrong (if anything).
If possible, you want to practice working on logic every day. If you can get a Monday-Wednesday-Friday class and do your studying on Tuesdays, Thursdays, and one day of the weekend, that would be a good plan.
I don't know why you might get the chance to take the logic class, but many people have the idea that students with dyslexia in particular (but not dyscalculia, so far as I know) cannot succeed in a logic class because of the symbol manipulation: there are symbols that mean different things if you write them upside down or backwards, and the order of the symbols matter. I have not found that to be true, but the dyslexic logic students I've known have made a point of either visiting their professors' office hours on a regular basis or hiring tutors to meet every week during the semester. I generally recommend that *everybody* do the assigned reading *before* class, but I especially recommend that for logic students with learning disabilities, because the more that the class is a review of something they've already seen, the better.
In addition, solving problems is a really important way to practice, and most students do not get enough of it. (That's one reason I recommend "Tarski's World.") One reason is that grading logic problem sets is slow and frustrating so only a small amount of problem-solving can be enforced. Again, if you try to solve problems with your tutor and/or before class, you will be able to make the best possible use of class time.
Most of the students I've known who found first-year logic classes "very hard" did not read the book and really try to understand it *before* the topics were discussed in class (some did not read the book at all) and/or did not do very many practice problems. In other words, they approached it as if it were a high school class rather than a college class. Some professors teach logic the way they were taught, and they weren't necessarily taught in a way that is ideal for college students who don't intend to pursue research in logic. However, I've known quite a few people who teach introductory logic and have only encountered one professor who taught logic so badly (and chose a book so inappropriate for the way he taught) that I would consider his students to have been unable to learn the subject even if they studied, and he has since retired.
I hope that this helps you decide whether the logic class would be a better fit than the math sequence. And I hope that whatever you end up taking, you are able to get enough support to get by. Good luck.