[Hiccup looks surprised at that--not because he finds what she says hard to comprehend, but because he can't believe that no one has explained this little oddity of Johto to her.]

Yeah, it-- It does that. [His mouth presses into a thin line as he tries to think how best to explain.] See, we can all be taken from different times, when we're brought here, I guess. Time for us will then 'freeze' until we go back, so we don't miss anything going on back home, and people back home won't miss us. For them, we're still there.