Alia columba ad limen volat, dum puella passeres et columbas quiete spectat.

Alia is an adjective meaning another or other. It is feminine nominative singular, matching columba, which is also feminine nominative singular.

So:

• alia = feminine nominative singular
• columba = feminine nominative singular

They agree because alia describes columba.

A useful nuance: alia often means another/other, while altera more specifically means the other one of two.

They are the same noun in different forms.

• columba = nominative singular: the dove as the subject
• columbas = accusative plural: doves as the direct object

So in this sentence:

• Alia columba ... volat = Another dove ... flies
• puella ... columbas spectat = the girl watches doves

Latin changes noun endings to show their job in the sentence.

Because ad takes the accusative case when it means to or toward.

• ad limen = to/toward the threshold

The noun is limen, liminis and it is a third-declension neuter noun. Its accusative singular is limen.

So:

• limen = nominative singular or accusative singular
• after ad, it must be understood as accusative singular

If you had limine, that would be ablative singular, which would not be used after ad.

Puella is nominative singular.

We know this because it is the subject of spectat:

• puella spectat = the girl watches

In first-declension nouns, the -a ending is often nominative singular, as in:

• puella = girl
• columba = dove

Because the two nouns belong to different declensions.

• passer, passeris is third declension
  • accusative plural: passeres
• columba, columbae is first declension
  • accusative plural: columbas

Both are direct objects of spectat, but they form the accusative plural differently.

So:

• passeres = sparrows
• columbas = doves

Here dum means while.

It introduces a subordinate clause showing an action happening at the same time as the main action:

• Alia columba ad limen volat = main clause
• dum puella passeres et columbas quiete spectat = while the girl watches the sparrows and doves quietly

So the sense is that the dove flies to the threshold while the girl is watching.

Both verbs are present active indicative, third person singular.

• volat = she/it flies
• spectat = she/he/it watches

They are third person singular because their subjects are singular:

• columba → volat
• puella → spectat

The present tense gives the scene as something happening now, or as a vivid narrative present.

Quiete is an adverb, meaning quietly or calmly.

It modifies spectat:

• quiete spectat = watches quietly

This is a good example of Latin using an adverb where English often uses an -ly word.

Latin word order is much more flexible than English word order because Latin uses endings to show grammatical function.

English depends heavily on position:

• The girl watches the doves is different from The doves watch the girl

Latin can move words around more freely because the endings already show who is subject and who is object.

In this sentence:

• alia columba is highlighted first
• the dum clause comes afterward
• the verb spectat comes at the end of its clause, which is very common in Latin

So the word order is not random, but it is less rigid than in English.

We know from the cases and the verb endings.

For example:

• columba = nominative singular → subject of volat
• puella = nominative singular → subject of spectat
• passeres and columbas = accusative plural → objects of spectat
• limen after ad = accusative of motion toward

So even if the words were rearranged, the endings would still tell us their roles.

Latin has no articles like English the or a/an.

So:

• puella can mean the girl or a girl
• columba can mean the dove or a dove
• limen can mean the threshold or a threshold

Context tells you which is most natural in translation.