Lancaster is unique in the sense that you study two additional minor subjects alongside your major. It means you don't have to choose which academic route you'd like to focus on quite yet... you're given an extra year to make sure you've made the correct choice.
I study English Language as my major, and Sociology and Criminology as my two minors. In the first year, you spend an equal amount of time on each subject; I have two hours in the lecture theatre and a one hour seminar, per subject. Despite Sociology and Criminology being my minor subjects, I will still be in the lecture theatre / seminar room with people who have taken those courses as a major. It's the same module for everyone in first year.
If you've applied for a joint-honours, then that will usually count as two of your three subjects. For example, a friend of mine is enrolled on a joint-honours for English Language and Creative Writing; he chose to study Philosophy as his minor. People tend to drop their minors after the first year, but I believe there is the option to change your degree scheme (whether it be changing completely, or changing to a joint-honours).
The above poster is completely correct - although it does depend on your course. Medicine and Law, for instance, can't study a minor. Some single honours can only do one (e.g. Maths) but a lot will be able to do two.