What is a noun and why is it so complicated?

Use morphology and syntax to make grammatical sense of the following sentence (mark all that the ova of all mammals except the monotremes undergo holoblastic segmentation. the -s inflection indicates that monotremes is a plural noun. the suffix -ic indicates that holoblastic is an adjective. the suffix -ation in the word segmentation is a noun-forming suffix denoting a process. the -s inflection indicates that monotremes is a possessive noun.

In a midsummer night dream, the mention of is an allusion to earlier english poetry

It is clearly expressed. what does that mean?