That will work, but not under strict 'refs'. Symbolic references are considered bad practice (but you can't always avoid them).

$testing = "Hello, World!\n";
$var = "testing";
$data = $$var;
print $data; # prints Hello, World!
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Using a hash is better, and hashes are useable under strict 'refs':

$hash{"testing"} = "Hello, World!\n";
$var = "testing";
$data = $hash{$var};
print $data;
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(You can remove quotes from hash keys that have no \W characters: $hash{testing}.)