#!/usr/bin/perl -w
use strict;         # in addition to using -w this will
                    # help you find more errors

# if you use strict then you have to declare your variables, usually using my
my %count = ("para",0,"sen",0);

while ( <> )                 # read a record (a line here) and set $_
  { 
    # a paragraph is any line that has at least one non-space character
    if ( /\S/ )   
       { $count{para}++; }
     # the g modifier allows you to loop through the string
     # matching successive occurences of the pattern
     while (  /[.?!]/g)      
       { $count{sen}++;   } 
     # use s/// to substitute the pattern
     # \w is a word character, 
     # $1 is the text that was matched between the ()
     # /g does the substitution for all matches in the string
     # /e evaluates the right part expression lc($1)
     s/([aeiou]\w*)/lc($1)/eig;
   }

# this is how you print a hash
foreach my $value (keys %count)
  { print "$value: $count{$value}\n"; }