"남자는 산을 오릅니다."
Translation:A man climbs a mountain.
My interpretation. Open for discussion.
(1) In English, there are verbs and phrasal verbs. When a preposition is added to a verb and give it a sense of direction or movement, the verb becomes a phrasal verb.
Verb --> verb + preposition --> Phrasal verb
e.g. "to go" is a verb. "to go up" is a phrasal verb. The preposition "up" is added to give the verb a sense of direction.
(2) Korean often prefixes an action verb with the infinitive form of another and makes it a motion verb. (This infinitive verb form has the same role as the English preposition.).
Action verb --> (Infinitive of another action verb) + Action verb --> Motion verb
e.g. 가다 (to go) is an action verb.
오르다 (to get to a high position, to ascend, to climb) is another action verb. 올라 is its infinitive form
--> 올라-가다 ( to go to a higher position, to go climbing, to climb up ) is a motion verb.
올라-가다 = to go climbing / to climb up
올라-오다 = to come climbing / to climb up
The difference here lies in the speaker's position, hence perception.
올라-가다 --> climb up (but away from the speaker)
올라-오다 --> climb up (but towards the speaker).
From Naver dictionary
운동, 놀이, 탐험 따위의 목적으로 산에 오르다 - Climb a mountain for the purpose of exercising, enjoyment, exploring.
So it seems that while 산에 오르다 describes the actual action of climbing a mountain, 등산하다 depicts an activity, i.e. mounting-climbing.
산에 오르다 = Climb a mountain => Action (Motion/Dynamic)
등산하다 = Do mountain-climbing => Activity (Stative)
This is my personal impression. I could be wrong. So any feedbacks will be most welcome.