In English, the verb tends to come directly after the subject. To find the subject ask the question, "What are the happiest and fairest days of the year?".
Subject: The early summer days on a farm
Subject Predicate: the happiest and fairest days of the year.
Note, the verb To Be has many forms;e.g., is, am, are, was, were, been. It links or joins the subject with its predicate, and it can be replaced with an equals sign, like this,
The early summer days on the farm = the happiest and fairest of the year.