Suppose I have 50 lines in my vim editor and I have to delete particular lines (5,9,16,28) in a single command.
It's unwieldy to manipulate on separate lines at once, but can be done:
:g/.../- Act on lines matching pattern
\v- very magic, less escaping for special characters in regular expressions.
%<num>l- match on line number
%5l|%9l|...matches the 5th line or the 9th line or ... .
:ddeletes the lines.
If it's just one line, or a range of lines, you could do
:5d for the fifth line, or
:9,16d for the range of lines from 9th to the 16th line (inclusive).