Learn Farsi: هر شب کتاب خواندن یک عادت خوب است. - Reading a book every night is a good habit.

Just like in English ("every night"), the word هر (every/each) is always followed by a singular noun in Farsi. You use شب (night) rather than its plural form because you are focusing on each individual night.

Why is the dictionary form of the verb (خواندن) used here instead of a conjugated verb?

In Farsi, the infinitive form of a verb (which always ends in -ن) can act like a noun. This is exactly like adding "-ing" to a verb in English to make a noun (a gerund). So, خواندن here translates to "reading".

Why does کتاب (book) come before خواندن (reading)?

Farsi puts objects before verbs. This rule still applies even when the verb is being used as a noun phrase. So instead of "reading a book", Farsi literally says "book reading" (کتاب خواندن).

How do the words link together in یک عادت خوب (a good habit)?

The word یک (a/one) comes first and just sits next to the noun. Then, the noun عادت (habit) is linked to the adjective خوب (good) using an unseen ezafe (an "eh" sound). You pronounce the whole phrase as yek 'ādat-e khub.