What is "rhostrehwfa"

Rhostrehwfa is a village in southern-central Anglesey, located southwest of Llangefni. To the southeast is the Malltraeth Marsh. It is "situated at a prominent point on the crest of a ridge overlooking the River Cefni valley to the south."It contains the Capel Pisgah and several holiday cottages. It is in the community of Llangristiolus and the Bodffordd electoral ward.