This is the 3753rd most frequent Korean word.
센
"센" means "strong" or "powerful."
Here, '센' is used as an adjective describing the intensity or strength (센 힘), meaning 'strong' or 'intense'.
그녀는 매우 센 힘으로 문을 열었다.
She opened the door with very strong force.
In this sentence, '센' modifies '햇빛' (sunlight) to indicate its strength and brightness, emphasizing the intensity of the sunlight.
센 햇빛 아래서 너무 더웠다.
It was too hot under the strong sunlight.
Here, '센' describes a person (센 사람), implying emotional or mental strength, portraying resilience and determination of character.