Question

what are the significance of lines of latitude ​

Answer 1

The most important line of latitude is the equator, which runs horizontally around the fattest part of the earth. The most important longitude line is the Prime Meridian which runs vertically and goes through Greenwich, England.

Answer 2

There are many lines of latitude that have local significance. For me, the 49th line of latitude north of the equator is significant because it forms the boundary between the United States and Canada in my region. The 46.5807 line of latitude is important because that is where I live.