What's in store for a person is what that person will experience or encounter at some point in the future. We usually use this expression when we don't know exactly what will happen or when we don't want to specify. If a friend is moving to a new place, you can ask, "So what's in store for you when you get there?" You're basically asking if your friend knows what to expect when he arrives at his new town. If he isn't sure what to expect exactly, he can reply, "I'm not sure yet, but I'm excited to see what's in store for me when I get there." In this case, he may have a friend there who has already found him a job and an apartment. He isn't sure what kind of job or apartment it will be, but he's excited about the possibilities.
A: So what's in store for you when you move to Alaska?
B: I'm not exactly sure yet, but I'm excited. I've always wanted to live there.
A: Do you have to find a job when you get there?
B: Yeah. I'll probably work in the fishing industry for awhile until I find a writing job.
A: Well, don't forget to bring your winter coat with you, and stay away from the bears.
B: Oh definitely. I know what's in store for me if I come close to one of those grizzlies.
So what's in store for you when you finish your English course or when you've mastered English? You can say, "I'll find a new job where I can speak English everyday," or "I will continue practicing and studying English," or you can say, "I'm not sure what's in store for me yet, but I will definitely try to use English as much as I can."
Don't forget to practice. Good luck!