You might need to elaborate on what exactly you're doing with the two colors, but it in stranded knitting it means to keep the color that you want to be a bit more dominant on 'top'--the strands don't cross in the back, but one is above the other and the one on top supposedly shows up more.
In intarsia it may refer to crossing the yarns when you switch color so the color that you're dropping is on top of the color you are picking up so they twist on he back to prevent holes.
Or it might mean neither.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry