What is Real-Time saving?

Well, I was watching the Supercard DSTwo video, and I saw he did something and the game got to a point he was not before he did.Then I remembered Real-Time Saving could be possible.
I have:
R4 SDHC (1.34, with Pandora)
R4i SDHC Upgrade (1.09c, latest for my card)On both there is listed that they have Real Time saving.How do I do this, and what is it?