Either of the literals "\\\\" or '\\\\' interpolate in a m// or qr// operator to a pair of backslash characters \\ (escaped-backslash) which match a single backslash character.
c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"print '\\';
print '\\\\';
print qq{\\};
print qq{\\\\};
;;
print qr{\\};
my $bb = '\\\\';
print qr{$bb};
;;
my $PathOnly = 'c:\Dir1\Dir2\Dir3';
;;
my @SubDirs = split(m/\\/, $PathOnly);
dd \@SubDirs;
;;
@SubDirs = split($bb, $PathOnly);
dd \@SubDirs;
"
\
\\
\
\\
(?-xism:\\)
(?-xism:\\)
["c:", "Dir1", "Dir2", "Dir3"]
["c:", "Dir1", "Dir2", "Dir3"]
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