The question seems to be incomplete but based on the given, this must be about dihybrid cross.
Dihybrid cross refers to the cross which involves two different traits. If the question is pertaining to the cross between pea plants, R and Y must be referring to the seed shape and color, respectively.
Take note that capital letters denote dominant traits while lowercase letters denote recessive traits.
For the seed shape, R refers to "round" while r refers to "wrinkled" seeds. For the seed color, Y refers to "yellow" while y refers to "green" seeds.
If we are going to cross plants which are heterozygous for the said traits (RrYy), we will get a 9:3:3:1 phenotypic ratio, as shown in the attached Punnett square.
