Learn Hardcore Finnish: Tytär haluaa ensin lelukauppaan, koska siellä on hänen suosikkinsa. - The daughter first wants to go to the toy store, because her favorite is there.

lelukauppaan (illative case) already means to the toy store / into the toy store.
So haluaa lelukauppaan is understood as wants to go to the toy store.

You can absolutely say the longer version:

Tytär haluaa mennä ensin lelukauppaan...

Both are correct; the shorter one is just more colloquial and natural when the context clearly involves movement.

What does the -an ending in lelukauppaan mean?

The ending -an here is the illative case, which basically expresses movement into or to something.

lelukauppa = toy store
lelukauppaan = into the toy store / to the toy store

In English you need a preposition (to), but in Finnish the case ending replaces that. So the idea of to is built into -an.

Why is there no word for “to” before lelukauppaan?

Finnish normally doesn’t use separate prepositions like to for directions. Instead, it uses case endings:

kotiin = to home (illative)
kauppaan = to the shop (illative)
puistoon = to the park (illative)

So lelukauppaan already contains the meaning of to the toy store, and adding an extra word for to would be ungrammatical.

What is the role of ensin in the sentence, and where can it go?

ensin means first / first of all / before anything else.

In this sentence:

Tytär haluaa ensin lelukauppaan...
= The daughter wants to go to the toy store first (before going anywhere else).

You could also say:

Tytär haluaa lelukauppaan ensin...

Both are possible, but ensin most often comes before the part it modifies, so ensin lelukauppaan feels a bit more neutral. The meaning doesn’t really change; it’s a word-order preference.

How does koska work here, and could the order of the clauses be reversed?

koska is a subordinating conjunction meaning because.

Here you have:

Tytär haluaa ensin lelukauppaan, koska siellä on hänen suosikkinsa.
= Main clause + koska-clause.

You can also put the koska-clause first:

Koska siellä on hänen suosikkinsa, tytär haluaa ensin lelukauppaan.

Two important points:

A comma is always used between the main clause and a koska-clause.
koska in standard modern Finnish mainly means because (for when you normally use kun).

What exactly does siellä refer to, and why is it used instead of other words for “there”?

siellä means there (in that place) and refers back to the location already mentioned, i.e. lelukauppa (toy store).

lelukauppaan = to the toy store (direction)
siellä = there (in that place; in the toy store)

Why siellä?

siellä is used for being in some place that has just been mentioned or is known from context.
siinä = there in/on that specific spot (very concrete, close to you or previously pointed at).
tuolla = over there (often a bit more physically distant / being pointed at).

Here, you’re talking about “the toy store” as a place already known in the conversation, so siellä is the natural choice.

Why do we have both hänen and the ending -nsa in hänen suosikkinsa? Isn’t that like saying “her her favourite”?

It does look redundant from an English perspective, but in Finnish this is the normal way to express a 3rd-person possessor.

hän = he / she (gender‑neutral)
hänen = his / her (genitive)
suosikki = favourite
suosikkinsa = favourite + possessive suffix -nsa = his/her/their favourite(s)

So hänen suosikkinsa literally is:

her favourite(s), where
- hänen marks the owner, and
- -nsa marks that the noun belongs to a 3rd person.

In practice, for 3rd person, the pattern hänen + [noun] + -nsa is very common and feels natural:

hänen kirjansa = his/her book(s)
hänen koiransa = his/her dog(s)
hänen suosikkinsa = his/her favourite(s)

Is suosikkinsa singular or plural here? And why is the verb on and not ovat?

suosikkinsa is formally ambiguous: it can mean either:

his/her favourite (one)
his/her favourites (several)

The context usually decides whether you imagine one thing or several.

As for the verb:

In Finnish existential sentences of the type “There is/are X somewhere”, the verb olla is almost always in 3rd person singular (on), even if X is plural:
- Pöydällä on kirjoja. = There are books on the table.
- Siellä on hänen suosikkinsa. = Her favourite(s) are there.

Using ovat here (Siellä ovat hänen suosikkinsa) is possible but sounds more like you’re pointing out already known, specific items rather than just stating their existence. In everyday speech, on is much more common in this structure.

Does hän / hänen tell us the gender of the daughter?

No. hän (and its genitive form hänen) is gender‑neutral.

hän = he / she
hänen = his / her

The fact that the subject is tytär (daughter) tells you it’s a female person, but the pronoun hän/hänen itself does not carry any gender information. Finnish does not grammatically distinguish he vs she.

Why is it just Tytär, without a word like “the” or “my”? How do I know if it means the daughter, a daughter, or my daughter?

Finnish has no articles (no words like a or the), so Tytär can correspond to several English possibilities depending on context:

The daughter
A daughter
My/our daughter (if that’s clear from the situation)

In everyday speech, if you’re talking about your own child, Tytär haluaa ensin lelukauppaan... will usually be understood as My daughter wants to go to the toy store first... because that’s the most natural context. To make it fully explicit, you could say:

Minun tyttäreni haluaa ensin lelukauppaan... = My daughter wants to go to the toy store first...

How is haluaa formed from haluta, and what does its form tell us?

The dictionary form is haluta (to want).
The present tense conjugation is:

minä haluan – I want
sinä haluat – you want (sg)
hän haluaa – he/she wants
me haluamme – we want
te haluatte – you want (pl)
he haluavat – they want

So haluaa is the 3rd person singular present form (hän haluaa), matching the subject Tytär (the daughter). The double aa is just how this verb’s 3rd person singular present is formed; it doesn’t add any special meaning by itself.