Not exactly what? She'll never know. Probably. Reira is eager to explain after all, or at least enough that she's heading for one of the larger pockets these pants are equipped with. It makes it much easier to store her duel disk- which she holds between two hands.

"Solid vision is what the holograms from a duel disk, or a field generator, are called...They're holograms that you can touch, and feel, and the monsters that come out of it are real..."

As if realizing that 'real' can be a bit vague, she adds. "...They even have feelings, and spirits."