This is the 5042nd most frequent Korean word.
길이는
"길이는" means "length is" in English.
길이는 is used to specify the length of an object, indicating its measurement in a physical context.
이 책의 길이는 30센티미터입니다.
The length of this book is 30 centimeters.
Here, 길이는 expresses a duration or span of time for the lecture.
강의 길이는 얼마나 되나요?
How long is the lecture?
In this case, 길이는 refers to the length of hair, describing a physical attribute with a qualitative aspect.