What does a opener do exactly? (USA)

This morning I agreed to come in when my favorite manager (she's such a sweetheart) it was my day off and they were shorthanded. I went in at 5:30. During the early morning shift while waiting for more employees to arrive so I could leave she asked me to consider being an opener. I'm currently weighing the pros and cons of this decision.

My question is this ...What do opening SERVICE people do exactly. I've been at our store about 18 months. I've never worked food prep. What is involved in that first hour before the drive thru opens. For the next few days I'm going to test if I can go to sleep and wake up in time. I don't want to hear how horrible you think opening is. No personal opinions please. Just because you had a bad experience doesn't mean I would. I actually enjoy my coworkers and we get along really well. Just what do openers do?