Haudh-en-Arwen, Ladybarrow (also called Tûr Haretha), was the funeral mound of Haleth.
Haleth was the daughter of Haldad of the Haladin, who led her people westward across Beleriand and founded the settlement of Men in the Forest of Brethil. After her death, the People of Haleth - as they had become known - raised a barrow (known as Tûr Haretha or Haudh-en-Arwen) for her in the Forest.
The Sindarin term Haudh-en-Arwen can roughly be translated as "Ladybarrow". The actual translation would be "Mound of the Noble Maiden". The element Arwen had no direct connection with Arwen Evenstar, who lived millennia after Haleth's time, but it does give an insight into the origin of her name. Sindarin arwen means literally "high maiden", and is translated here as the "lady" in 'Ladybarrow'.
Tûr Haretha is the Mannish name of "The Ladybarrow".