In this case I would consider the term "Favored Enemy" (from the phrase "one additional favored enemy") as referring to the class feature itself, with the text:

Choose a type of favored enemy: aberrations, beasts, celestials, constructs, dragons, elementals, fey, fiends, giants, monstrosities, oozes, plants, or undead. Alternatively, you can select two races of humanoid (such as gnolls and orcs) as favored enemies.

So when you gain that class feature again you would gain exactly what it says, every time you gain it; unless the feature says otherwise, of course (e.g. you may not choose the same favored enemy twice).

All creature types

A monster is defined as any creature that can be interacted with and potentially fought and killed.

The monster manual defines monster as the above. And just from this you can get your answer: this spell works on basically everything.

You attempt to beguile a creature that you can see within range.

The spell works on any type of creature assuming it meets the other requirements in the spell description. But there are no types excluded.

See this question for an in depth discussion on what the word creature means in game terms.

To quote from the answer in that thread though:

Creature is basically every living breathing (or undead) thing big enough to be considered at least CR0 (give or take).

So the spell works essentially on any thing adventurers might come across.