Let's go line by line:

# Splits the contents of $16 on commas into array @_1
@_1= split "\,",$16;

# If @_1 has only one element force $time to integer
# Does $time already have a value? That's not apparent in 
# this snippet.
if($#_1 eq 0){
$time = int ($time);
}

# If @_1 has two elements set $time to the first one
# remove any commas (Although those should have been taken
# care of by the split above)
# And multiply $time by 1000
if($#_1 eq 1){
$time=$_1[0];
$time=~ s/\,//g;
$time*=1000;
}

# If @_1 has 2 or 3 elements simply set $time to 1000
if($#_1 eq 2){ $time=1000;}
if($#_1 eq 3){$time=1000;}
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This code seems like it is splitting up a large number with commas in it a la 1,000,000,000 or something. Perhaps Number::Format could be used?

HTH