「山」 (yama) means "mountain." It refers to a large natural elevation of the earth's surface. You use 「山」 when talking about hiking, climbing, or seeing a tall landform. Many beautiful 山 can be found in Japan, offering scenic views.

地(ち)面(めん)が高(たか)く盛(も)り上(あ)がった自(し)然(ぜん)の大(おお)きな地(ち)形(けい)です。登(と)山(ざん)によく行(い)きます。