@@-1,7 +1,6@@
That tells you what lines of the files the following change hunk apply to.
- -1 means that the following change hunk starts on line 1 of the original file.
- 7 means that the change hunk applies to 7 lines of the original file.
- +1 means that the change hunk starts on line 1 of the new file.
- 6 means that the change hunk applies to 6 lines of the new file.
In the change hunk that follows, lines preceded with a -
were deletion lines, lines preceded with a +
were addition lines, and lines preceded with a (space) were unchanged.
Reference: diff - Unified format