
Your girl has 2 copies of the black mask gene (so genetically she is a black with a black mask) this means every puppy she produces will at least have one copy of this gene making them also have a black mask regardless of what the male has.
She has one copy of the dominant black gene and one copy of the recessive non black gene. This makes her self black but able to produce colours that are determined by the A locus (sable, tan, agouti and rec black) so if the stud has 1 or 2 copies of the recessive non black gene they can produce non black puppies depending on what A gene combos they have.
Your girl has the tan gene and recessive black gene. Had she not of had a copy of the dominant black gene she would of been black tan (although the black mask would have covered a lot of or all of the tan mask). This means if the stud also had a tan gene or two they could produce tans with black masks, if the stud had a recessive black gene or two they could produce recessive black. if the stud had 2 sable genes they wont produce any tans or rec blacks.
She also carries a copy of the blue gene. So if the sire had 1 copy of the blue gene or was blue they could produce blues. If the stud does not have any blue genes no blue puppies will be produced.
BUT, blue and any of the tans (black tan, blue tan, choc tan, lilac tan) are not recognised colours in the breed and are a fault. Non standard colours in French bulldogs are SO over bred at the moment thanks to commercial breeders and pet breeders breeding purely for colour. So if you did a pairing that could produce a colour fault those puppies cant be registered under their colours, they would be registered as Colour Not Recognised By KC.
The most important thing in the breed is the health testing spicily as due to the huge increase of people breeding them for fashion and colours more health issues are sadly on the rise. If you haven't already this would mean Eye testing, DNA test - HC-HSF4, DNA test - DM and Participation in French Bulldog Health Scheme - this includes tests such as BOAS assessment, Spine xray, Nostrils Grading, Heart Test, Patella score.
Its also important you only pick a stud who has also had theses health tests. Idealy the