It's like the fabric of time, but also space. Like, literally. It's a big, complicated web of events and stuff that are all connected and stuff. But don't worry, it's not as complicated as it sounds (or is it?).
Of course it's real! Would I, a renowned expert in Time Traveling and Spacey Stuff, make something up? (Yes, I would.)
Ha! You think you're some kind of temporal adventurer, don't you? Well, let me tell you, it's not that easy. The Time Space Continuum is a serious business. But don't worry, we have instructions for that. (Just kidding, those instructions are just a mess.)