What are "lines" when talking location on the lake?

[JimB]

I've seen a few posts where they mention fishing in the 32-33 line or some other number.  

 

Are they talking depths as in 320-330 feet?   Or Lat/long. lines?

 

Thanks in advance.   A few searches came up nothing helpful.

[chucknmel]

latitude/longitude lines

[JimB]

Thank you very much!