Use Python 3, NLTK, and the Carnegie Mellon University Pronouncing Dictionary to count the syllables in an English word or phrase.

syllable_counter.py

# NLTK is a suite of libraries for working with human language data: http://www.nltk.org
# NLTK allows us to access the Carnegie Mellon University Prounouncing Dictionary (cmudict)
# cmudict is a corpus that contains almost 125,000 words mapped to their pronunciations.
# This tiny app was inspired by Lee Vaughn's Impractical Python Projects

import sys
from string import punctuation
from nltk.corpus import cmudict

# load corpus and build dictionary
cmudict = cmudict.dict() 

def main():
    print_header()
    run_event_loop()

def print_header():
    print("-----------------------------------------------------")
    print("                Syllable Counter")
    print("-----------------------------------------------------")

def run_event_loop():
    while True:
        word = input("Enter a word or phrase <press Enter to exit>: ")
        if word == "":
            print("\nThanks for using Syllable Counter. Have a good day!")
            sys.exit()
        # note that use of fstrings requires Python 3.6+
        try:
            num_syllables = count_syllables(word)
            print(f"\nNumber of syllables in '{word}' is {num_syllables}.")
            print()
        except KeyError:
            print("\nWord not found. Check your spelling or enter a new word.\n",
                  file=sys.stderr) # sys.stderr prints in red font, fyi
        except Exception as e:
            print(f"There was a problem processing this request. Details: {e}",
                  file=sys.stderr)

def count_syllables(words):
    """Use corpus to count syllables in English word or phrase"""
    # prep word or prhase for syllable counting
    words = words.replace("-", " ")
    words = words.lower().split()
    num_sylls = 0
    for word in words:
        word = word.strip(punctuation)
        if word.endswith("'s"):
            word = word[:-2]
        else:
            # [0] in case there are multiple pronunciations, default to first
            for phonemes in cmudict[word][0]:
                for phoneme in phonemes:
                    if phoneme[-1].isdigit():
                        num_sylls += 1
    return num_sylls

if __name__ == "__main__":
    main()