Columba alba e tecto descendit et aquam e parva piscina bibit.

Because alba has to agree with columba.

• columba is a feminine singular noun.
• An adjective modifying it must also be feminine singular.
• So alba means white in the feminine singular form.

This is called agreement: Latin adjectives agree with their nouns in gender, number, and case.

Also, grammatical gender does not always mean biological sex. Columba is grammatically feminine, so the adjective is feminine too.

Because Latin word order is much more flexible than English word order.

In English, we usually say white dove.
In Latin, both columba alba and alba columba are possible.

Very often, an adjective comes after the noun in Latin, especially in simple descriptive phrases. So columba alba is perfectly normal.

Latin uses endings more than word order to show grammatical relationships, so adjective position is freer than in English.

Because it is in the nominative case, which is the case normally used for the subject.

• columba is nominative singular
• alba agrees with it, so it is also nominative singular feminine

The verbs descendit and bibit are both third person singular, so they match a singular subject: the white dove.

Because aquam is the direct object of bibit.

The verb bibit means drinks or drank, and the thing being drunk goes into the accusative case.

So:

• aqua = water, in the nominative or ablative form depending on context
• aquam = water, as a direct object

Here the dove is drinking the water, so Latin uses aquam.

Because the preposition e means out of or from, and it takes the ablative case.

So:

• tectum becomes tecto in the ablative singular
• piscina becomes piscina in the ablative singular

Even though piscina looks the same in the nominative and ablative singular, here it is ablative because it follows e.

So:

• e tecto = from the roof
• e parva piscina = from the small pool

Because parva is describing piscina, and both words must agree in case, number, and gender.

Since piscina is ablative singular after e, the adjective must also be ablative singular feminine:

• nominative: parva piscina
• accusative: parvam piscinam
• ablative: parva piscina

So here parva piscina is ablative because of the preposition e.

They are just two forms of the same preposition, meaning out of or from.

Usually:

• ex is common before a vowel or sometimes certain consonants
• e is common before most consonants

So Latin can say:

• e tecto
• ex aqua
• ex urbe

In many texts, the choice is partly a matter of sound and style. For a beginner, the important point is that e/ex both mean the same thing and both take the ablative.

In ordinary Latin spelling, these forms can be ambiguous.

• descendit can mean he/she/it descends or he/she/it descended
• bibit can mean he/she/it drinks or he/she/it drank

So the sentence could be read as present or perfect, depending on context.

Learners often rely on:

• the translation given
• the surrounding passage
• whether the story is being told in present or past time

This is very common in Latin: sometimes the form alone does not tell you everything.

Because Latin usually does not need subject pronouns when the verb ending already shows the person and number.

Both descendit and bibit are third person singular, so once columba alba has been given as the subject, Latin can simply continue with another singular verb.

So Latin says:

• Columba alba ... descendit et ... bibit

English often repeats the pronoun:

• The white dove descends and drinks
• or The white dove descended and drank

Latin normally does not need to add ea or another pronoun here.

Because Classical Latin has no articles.

English distinguishes between:

• a white dove
• the white dove

Latin usually just says columba alba, and the exact sense is understood from context.

So a Latin noun can be translated as:

• a dove
• the dove
• sometimes just dove

depending on the situation.

Yes, often they could.

Because Latin uses endings to show each word’s role, the order is more flexible than in English. For example, these could still mean essentially the same thing:

• Columba alba e tecto descendit et aquam e parva piscina bibit.
• Alba columba e tecto descendit et aquam e parva piscina bibit.
• E tecto columba alba descendit et aquam e parva piscina bibit.

Different orders can create different emphasis, but the grammar stays clear because of the word endings.

So in Latin, word order often tells you more about focus or style than about basic grammatical function.