What does this mean? How do you fill it in?
Such an entry denotes a message with plural forms, that is, a message where
-the text depends on an cardinal number. The general form of the message,
+the text depends on a cardinal number. The general form of the message,
in English, is the @code{msgid_plural} line. The @code{msgid} line is the
English singular form, that is, the form for when the number is equal to 1.
More details about plural forms are explained in @ref{Plural forms}.