"Fold BB to Steal HU" discussion

[Blue Lagoon]

I don't understand exactly what it is.
Does it mean: Folded to the SB, who open-raises, and BB folds.

Because in this situation, I play almost always, as stated in Fromm's DVD. Since a few weeks I adjusted but I still play almost 90% of my hands in this position.
But my "Fold BB to Steal HU" is around 40%. So what's that??
BTW, my "fold BB to steal" is around 50%.

I just started to think about that because I read p.89 of WITHG, and it's not clear for me.