This is the 13188th most frequent Korean word.
둘러싸는
"Surrounding" or "enveloping."
Here, 둘러싸는 means 'surrounding' as part of its descriptive function to explain the placement or arrangement of the tree around the entrance.
이 나무는 입구를 둘러싸는 역할을 합니다.
This tree serves the role of surrounding the entrance.
둘러싸는 in this sentence implies the act of encircling as visually enclosing something.
그 장면은 아름다운 경치로 둘러싸는 느낌을 줍니다.
That scene gives a feeling of being surrounded by beautiful scenery.
In this case, 둘러싸는 describes the geographical or physical surrounding of the city by mountains.