The Brecon Beacons is a mountain range

Mountain range

A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...

 in South Wales

South Wales

South Wales is an area of Wales bordered by England and the Bristol Channel to the east and south, and Mid Wales and West Wales to the north and west. The most densely populated region in the south-west of the United Kingdom, it is home to around 2.1 million people and includes the capital city of...

. In a narrow sense, the name refers to the range of popular peaks south of Brecon, including South Wales' highest mountain, Pen y Fan

Pen y Fan

Pen y Fan is the highest peak in South Wales and southern Britain, situated in the Brecon Beacons National Park. At above sea-level, it is also the highest peak in Britain south of the Snowdonia mountain range...

, and which together form the central section of the Brecon Beacons National Park (Parc Cenedlaethol Bannau Brycheiniog). The name is also commonly used to refer more broadly to the entire national park which includes ranges both to the east and the west of the central Beacons.
The Brecon Beacons range, in its truest sense, consists of the mountains to the south of Brecon

Brecon

Brecon is a long-established market town and community in southern Powys, Mid Wales, with a population of 7,901. It was the county town of the historic county of Brecknockshire; although its role as such was eclipsed with the formation of Powys, it remains an important local centre...

.