Welcome! The front end team is one of the most important roles in the store (though really, the store wouldn't function with any of the roles missing). We are the first impression a guest gets when they enter, and the last impression they get as they're leaving. As long as you're friendly, accommodating, and make sure you're taking care of the guests, you'll do great!
The hardest part is learning the POS. Once you get all the functions down, plus the little cheats to take care of guests when something isn't working right, it's gravy. The security tags are easy enough; there are a few different types of spider wraps, so you'll just have to get experience with the different kinds and how they open. It isn't hard, I promise!
My ETL-SE has me make a break schedule when I first get in and mandate the breaks to my team, which is what the former GSAs used to do. Every ETL-SE and SETL are different, though, so it's a good question to ask your particular store when you first start.
Listen to your SETL's expectations, accept feedback, and try to have fun!