listlabels.py

import pickle
import os.path
from googleapiclient.discovery import build
from google_auth_oauthlib.flow import InstalledAppFlow

SCOPES = ['https://www.googleapis.com/auth/gmail.modify']

def main():
    creds = None

    flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
    creds = flow.run_local_server(port=0)

    with open('token.pickle', 'wb') as token:
        pickle.dump(creds, token)

    service = build('gmail', 'v1', credentials=creds)

    results = service.users().labels().list(userId='me').execute()
    labels = results.get('labels', [])

    print("[Labels_name] - [Label_id]:")
    for label in labels:
        print(label['name'], "-", label['id'])

if __name__ == '__main__':
    main()