If he is solid lavender, and she is lavender cuckoo, then breeding them together will give solid lavender daughters and lavender cuckoo sons.
If you have been reading other thread you may already know this:
--lavender is a recessive gene that dilutes other colors (black becomes gray, red/gold becomes yellow or cream-colored, white stays white).
--That lavender dilution can happen on chickens that would otherwise be many different colors, and it gets called by different names. So a solid black chicken becomes a solid lavender chicken (usually just called "lavender.") A black chicken with white barring becomes a "lavender cuckoo" chicken. A chicken with certain patterns of red/gold and black is turned into an "Isabella" chicken. A chicken with the Mille Fleur pattern becomes a "Porcelain" chicken.
--For breeding predictions, you need to understand how the recessive lavender gene works, and then figure out what underlying colors & patterns are present and how they interact.
I think you are working with base colors of solid black (rooster) and black with white barring (hen), but it's always a little hard to tell from pictures, and there is also the chance that they may be carrying recessive genes for various other color combinations. Breeding them together will produce chicks that are pure for the lavender gene, but I can't be sure what other color/pattern genes may pop up in a cross. So they might produce some lavender-diluted chicks with different (unexpected) base colors.
