read words from the keyboard and store them

[Larz60+]

Here are some of the things that were incorrect:

from random import randrange
lista2 = []
a = True
# Set word to empty string
word = ''
i = 0

# made get_word a function as it needs to be called several times
def get_word():
    while word == '':
        # don't need i here
        # i=i+1
        # indentation was off on next line, added space after :,
        # added lower here rather than later, added spaces between operators
        b = input('give a word: ').lower()

        # following can be done better and needs to be redirected to run again:
        # if b == ('',' ',''):
        #     print('one word only.')
        word = b.split()
        if len(word) > 1:
            print('one word only.')
            # Set word back to '' so loop continues
            word = ''
        print('the word has been given')
    return word

# lista2.append(b)     
# b.lower()
# if b==lista2[i]:

# if b=='end':
#     break
# word==word+1
# if word<5:
#     print('very short number of words')
# print(b)
# print (word)
# print (lista2)

This will allow you to call get_word as many times as needed.
I didn't finish, but this will get you started