I want to filter out words with one letter in a string (pig latin translator)

[perfringo]

If I understand correctly 'the translation' means that first character is moved to an end and 'ay' is added to all words which are longer than 1 letter.

One possibility to create translate function and then use it on all words in sentence.

def translate(word): 
    if len(word) == 1: 
        return word 
    else: 
        return f'{word[1:]}{word[0].lower()}ay'

Then just:

>>> sentence = 'Climb a tree'                                                                                                                                                
>>> ' '.join([translate(word) for word in sentence.split()])                                                                                                                 
'limbcay a reetay'

This must be further developed. It will not work as expected with the punctuation at the end of sentence and there is no rules for capitalisation of words.