This is a reoccurring question I have, but why is "mae" necessary here? I though "yn" was "is" as in owen is thinking... Any help would be greatly appreciated thanks.
Because you are mistaken. Welsh is a Verb-Subject-Object language so the verb i.e "is" comes first and therefore "Mae" means "Is". "Yn" (in this context) is an untranslateable verbal particle which is used to connect a form of "Bod" to a noun, adjective or verb-noun (causing a soft mutation on the first two).