Ya, it returns the number of symbols

//echo -a $symbols(fhdl34@kals:asd k2")

This should give 3

You can only check for the number of symbols if you want, but it's probably better to check the ratio of symbols to letters/numbers as well as the length of the message

if ($len($1-) > 10) {
var %ratio = $calc($symbols($1-)/$len($1-))
if (%ratio > 0.5) { do something }
}