Regular and irregular nouns:
For regular nouns we simply add -s to the end of the word:
For regular nouns that end in s, ch, sh, x or z we can use the ending -es
For regular nouns that end in -f or -fe we remove the f or fe and add ves
For regular nouns that and in a CONSONANT + Y we remove the y and add ies
For regular nouns that and in a CONSONANT + O we add es
For irregular nouns sadly we have to memorise these as they are not the same.
For more information you can also watch this video for a short refresher