noun
hills and fields; countryside
Refers to natural, undeveloped areas outside the city; often used in contexts of nature, hiking, or rural scenery.
週末は野山を散歩するのが好きです。
I like walking in the hills and fields on weekends.
野山の緑が美しい季節になった。
It's the season when the greenery of the countryside is beautiful.
Compound of 野 (の, 'field, plain') and 山 (やま, 'mountain, hill'). The combination straightforwardly denotes open fields and hills.