If you mean how do you capture output from such a tool into Perl, then where the rules of the "language" are simple enough, as in this case, the match operator can be used to detect and read the data.

use strict;
use warnings;
use POSIX ":sys_wait_h";
my $pid = open my $filehandle, "| speedfan";
                                # or whatever command it is
my ($ltemp, $rtemp, $hdo);
while( <$filehandle> ) { #reads the line into predeclared $_
    # per line loop of output e.g. ...
    /^Local Temp:\s(\d+)C/ and $ltemp = $1 and next;
    /^Remote Temp:\s(\d+)C/ and $rtemp = $1 and next;
    /^HDO:\s(\d+)C/ and $hdo = $1;
}
close $filehandle;
waitpid $pid,0; # wait for subprocess to terminate
# $ltemp, $rtemp and $hdo now contain the temperatures.
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In this case we assumed that the temperatures matched the expression \d+ (1 or more digits). A slightly more sophisticated expression is needed to match floating point data.