Hi. If you are in your second year at university, you are called a sophomore.
Here's a couple of sentences you can say:
I am a sophomore in college. This is my second year at my university. I'm in my sophomore year. I'm in my second year of college. I have studied for two years at my university.
Here is what each class is called:
First year or freshman
Second year or sophomore
Third year or junior
Fourth year or senior
Fifth-year and beyond or super-senior