* Hwfa refers to a well or spring, and is often used to refer to holy wells, places of pilgrimage, and healing sites.
* Môn is the Welsh name for the island of Anglesey.
So, Hwfa Môn is a place on the island of Anglesey that is known for its holy well. There are several places on Anglesey that could be referred to as Hwfa Môn, so it's helpful to have more context to know which specific location is being discussed.