Infans in cubili cubare non vult, sed matrem vocat et ridet.

Infans is nominative singular. It is the subject because it is the one doing the actions: vult, vocat, and ridet.

The verb endings also help:

• vult = he/she wants
• vocat = he/she calls
• ridet = he/she laughs/smiles

So infans is the one performing all of those actions.

Latin does not have definite or indefinite articles like English the and a/an.

So:

• infans can mean the baby/child or a baby/child
• matrem can mean the mother or a mother

The context tells you which is most natural.

Because in cubili expresses location: in/on the bed or in the bed.

With in:

• in + ablative = location, in/on/at
• in + accusative = motion toward, into/onto

So:

• in cubili = in bed / on the bed
• in cubile would mean into bed

Here the idea is location, not movement, so Latin uses the ablative.

The form cubili could look like either dative or ablative singular, but here it must be ablative because it follows in in the sense of location.

So even though the form is ambiguous by itself, the preposition tells you the case.

Because after vult Latin normally uses an infinitive, just as English uses to + verb after wants.

So:

• vult cubare = wants to lie down / wants to be in bed

Here:

• cubare = to lie down / to be lying
• vult = wants

This is a very common Latin pattern:

• vult venire = he/she wants to come
• potest currere = he/she can run
• debet manere = he/she ought to remain

Because they are related words.

• cubare = to lie down
• cubile = bed, couch, resting place

They come from the same basic idea of lying down or resting. So the sentence has a natural connection: in cubili cubare = to lie in bed.

In sense, it negates the whole idea: does not want to lie down.

Latin word order is flexible, so cubare non vult and non vult cubare express basically the same idea. The sentence as written puts cubare first and then finishes with non vult, which can give a slight emphasis to the action being refused.

So the natural English meaning is:

• does not want to lie down not
• wants not to lie down as a stiff literal phrase

Because matrem is the direct object of vocat.

The child is calling the mother, so the person being called is put in the accusative:

• mater = nominative, mother
• matrem = accusative, mother as direct object

This is the normal pattern with a transitive verb like vocare.

Yes. Latin often states the subject once and then continues with more verbs referring to the same subject.

So this sentence works like:

• The child does not want to lie in bed, but the child calls the mother and the child laughs

English usually repeats the subject less often too, but Latin is especially comfortable leaving it out once it is clear.

Because the verb endings already show the person and number.

• vult = he/she/it wants
• vocat = he/she/it calls
• ridet = he/she/it laughs

Since infans is already named, Latin does not need to add a separate pronoun unless it wants special emphasis.

Sed means but. It introduces a contrast:

• the child does not want to lie in bed
• but calls the mother and laughs

So sed connects the two parts while showing that they contrast with each other.

They are all present indicative active, third person singular.

• vult = wants
• vocat = calls
• ridet = laughs/smiles

The infinitive cubare is also a present infinitive.

Yes. Latin word order is much freer than English word order because the endings show the grammatical roles.

For example, you could also say:

• Infans non vult in cubili cubare, sed matrem vocat et ridet.

That would mean essentially the same thing. The version you were given places cubare non vult together at the end of the first clause, which gives a neat emphasis to the child’s refusal.

So in Latin, word order often affects style or emphasis more than basic meaning.