This section is devoted to nouns and things associated with nouns, like articles and adjectives. An article is just a fancy name for the little words meaning the (definite article) and a/an (indefinite article). English has only one such word (two for indefinite, if you include an), but Italian has several. Knowing things about the Italian noun you use (like its gender and number) allows you to choose the correct article to go with it. Adjectives are words that describe nouns. Just like the articles, their endings are variable, depending upon the gender and number of the noun they describe. There are many different kinds of adjectives, including descriptive adjectives (describing external or internal characteristics, like big or brave), possessive adjectives (like my, your, etc. describing ownership or relationship), demonstrative adjectives (the words for this and that), and indefinite adjectives (the words for some, many, all, etc.).
Once you learn adjectives to describe nouns, you may want to learn adverbs, which describe verbs. Many adverbs derive from adjectives.
Once you learn how to describe nouns and verbs, you may wish to compare them. The comparative section is a good place for that.