This exercise is a grammar exercise with music.
Start the audio file and listen to nouns and their plural form. You hear a group of words with a plural form finishing in -(e)n, in -e , in -er and in -s and a group of words which do not change in the plural.
For a good result you should first try to visualize the meaning of the words. Then repeat them with you inner voice. If this helps you to learn German articles and plural forms, try to do this with your favorite musics.