Cuando mi hija tiene sueño, la arropo bien y le canto una canción muy despacio.

Because cuando here is a conjunction meaning when.

• cuando = when in a statement
  
  • Cuando mi hija tiene sueño...
• cuándo = when? in a question or indirect question
  
  • ¿Cuándo llega? = When is she arriving?
  • No sé cuándo llega. = I don’t know when she’s arriving.

So in this sentence, cuando has no accent.

Because the sentence describes a habitual action: something that usually happens.

• tiene sueño = she gets/is sleepy
• la arropo = I tuck her in
• le canto = I sing to her

So the idea is: Whenever my daughter is sleepy, I tuck her in well and sing her a song very slowly.

If you were talking about a specific future situation, Spanish would usually change the structure, for example:

• Cuando mi hija tenga sueño, la arroparé...

But in the original sentence, the present tense is the natural choice for a routine.

Because tener sueño is the normal Spanish expression for to be sleepy or to feel sleepy.

Literally, it looks like to have sleep, but you should learn it as a fixed expression:

• tener sueño = to be sleepy

A couple of useful comparisons:

• Tiene sueño = She is sleepy
• Está cansada = She is tired
• Tiene un sueño = She has a dream

Notice that tiene sueño has no article. If you add un, the meaning changes.

Here arropar means to tuck someone in, to cover someone up, or to wrap someone up warmly.

In this context, it usually means something like putting the blanket around the child properly before sleep.

So:

• la arropo bien = I tuck her in well / I make sure she’s nicely covered up

In Spain, this is a very natural verb to use with children at bedtime.

Because la is the direct object pronoun meaning her.

The verb arropar takes a direct object: you tuck in someone.

• Arropo a mi hija = I tuck in my daughter
• La arropo = I tuck her in

Since mi hija is feminine singular, the pronoun is la.

Because with cantar, the thing being sung is the direct object, and the person receiving it is the indirect object.

In this sentence:

• una canción = the thing being sung → direct object
• a mi hija = the person you sing to → indirect object

So Spanish uses le:

• Le canto una canción = I sing her a song / I sing a song to her

If you said la canto, that would mean I sing it (referring to a feminine direct object such as la canción).

Because unstressed object pronouns in Spanish normally go before a conjugated verb.

So:

• la arropo
• le canto

That is the standard pattern.

English often puts the object after the verb, but Spanish uses these short pronouns before it.

You’ll also see pronouns attached in other structures:

• infinitive: arroparla
• gerund: cantándole
• affirmative command: cántale

But with normal conjugated verbs like here, they go before.

Because mi hija is the subject of the first clause, but in the next actions she becomes the object.

Compare it in English:

• When my daughter is sleepy, I tuck her in and sing to her.

English also switches from my daughter to her. Spanish does the same thing:

• mi hija = subject in the first part
• la = direct object in la arropo
• le = indirect object in le canto

So the pronouns are not redundant; they are doing normal grammatical work.

Here bien means well, properly, or nicely.

It does not mean good as an adjective. It is an adverb, describing how the action is done.

So:

• la arropo bien = I tuck her in properly / nicely

It suggests care: making sure she is comfortably covered.

Literally, muy despacio means very slowly.

So the sentence says that the singing is done slowly, probably in a calm, soothing way.

That said, English speakers sometimes expect softly in this kind of bedtime sentence. In Spanish, despacio is mainly about speed, not volume.

If you wanted to emphasize quietly/softly, Spanish might use something like:

• bajito
• en voz baja
• suavemente

So muy despacio is natural, but it means slowly, not specifically quietly.

Yes, a little.

For example, you could also say:

• Cuando mi hija tiene sueño, la arropo bien y le canto muy despacio una canción.

That is still natural. The difference is mainly one of rhythm or emphasis.

What usually does not change is the position of the object pronouns with conjugated verbs:

• la arropo
• le canto

So the overall sentence is flexible, but those pronouns stay in their normal place.

Because that opening part is an introductory subordinate clause.

Spanish commonly uses a comma after a clause like this when it comes first:

• Cuando mi hija tiene sueño, la arropo bien...

It helps separate the when-clause from the main clause.

You will often see this in both Spanish and English with longer or introductory clauses.

A few key points:

• The h is silent.
• The j has the strong Spanish sound used in Spain, like a throaty h.
• Stress falls on the first syllable: HI-ja

A rough English approximation is EE-ha, but with a stronger Spanish j sound than English h.

So mi hija sounds roughly like:

• mee EE-ha

In most of Spain:

• canción is roughly kan-THYON
• despacio is roughly dess-PA-thyo

That is because in most Peninsular Spanish, c before i or e is pronounced like th in thin.

Also:

• canción is stressed on the last syllable because of the accent mark: can-CIÓN
• despacio is stressed on PA: des-PA-cio

If you hear Latin American pronunciation, those same words usually sound more like:

• kan-SYON
• dess-PA-syo