For simple recessive genes (I’m using R as an example, R is dominant and r is recessive):
R/R: non carrier, pure for dominant allele (e.g not recessive white). Shows dominant phenotype.
R/r: carrier, looks like the non carrier but can pass the recessive on to offspring. Shows dominant phenotype.
r/r: shows recessive phenotype (e.g recessive white or lavender)
Breed two non carriers, you will never get it.
R/R x R/R = R/R (100%)
Breed a carrier to a non carrier, you still never get it.
R/r x R/R = R/R (50%) and R/r (50%)
Breed a pure recessive to a non carrier, still won’t get it.
r/r x R/R = R/r (100%)
Breed two carriers, you will get some.
R/r x R/r = R/R (25%), R/r (50%) and r/r (25%)
Breed two pure recessives, you only get the same.
r/r x r/r = r/r (100%)
I hope this breaks it down to make it easier rather than making it seem more complicated!