This source package control file is generated by dpkg-source when it builds the source archive. This file contains a series of fields, identified and separated just like the fields in the control file of a binary package. Debian source.dsc file describes a source package.
This will create the file -build-deps_.deb and install it, and also install all the. Move into the extracted source folder and run: sudo mk-build-deps -i. Z file, and maybe also a.debian.*z file, then unpack the source package with: dpkg-source -x _.dsc.