He is learning how to use collective nouns.

That is one of the formal nouns.

Nominalization is the linguistic process of converting verbs or adjectives into nouns.

Kumiko is my best friend.

The twist in this novel surprises the readers.

The development of this essay is written very skillfully.

He is very careful in choosing words and phrases.

This full stop indicates the end of the sentence.

He finds it difficult to learn Japanese idioms.

It is important to maintain peace of mind by reading one scripture every day.