“靠山”常见的英文表达可以是 “lean against the mountain”（强调身体倚靠的动作）或 “be backed by the mountain”（侧重于描述位置或被山支撑的状态） ，具体使用哪个可根据语境来定。
例如：
He leaned against the mountain to take a rest.（他靠山休息了一下。）
The small village is beautifully situated, being backed by the mountain.（那个小村庄位置极佳，背靠大山。 ）