Okay, so scale degree names can get wacky. Just like the letter names for notes, the numbers we use to label scale degrees can go by different enharmonic names. And the term you use to describe a scale degree depends on how sharp or flat it is.
For example, here’s a lovely graphic that summarizes every possible scale degree in music. Double-sharp (x) numbers are in the outer ring, followed by the different sharp (#), natural, flat (b), and double-flat (bb) numbers for various intervals in the chromatic scale.
Looking at the scale degree “3,” for example, you might just refer to this interval as “3″ … or as “##2″ … or maybe you’d call it “b4.” But it doesn’t really matter because these different number names describe the same interval in a given key—that is, one that’s two whole steps above the tonic note. So no matter what you call it, you’re describing the exact same interval.
Of course, some of these scale degree names are a little obscure. For example, I can’t think of anyone who calls scale degree “1″ “#7″ or “bb2.” After all, the tonic is the tonic (!), so it usually just goes by the name “1.” And 7 hardly ever goes by the names “b1″ or “x6.”
So, for simplicity, these are the most common scale degree numbers you’ll hear musicians use music. The better you get at learning these musical terms, the better you’ll be at playing songs.