O cavalo bebe água.

O is the masculine singular definite article, meaning the.

So:

• o cavalo = the horse

In Portuguese, articles are used very often, sometimes more often than in English. With a basic sentence like this, o cavalo sounds natural and complete.

Because cavalo is a masculine noun.

In Portuguese, nouns have grammatical gender:

• o = masculine singular
• a = feminine singular

So:

• o cavalo = the horse
• a égua = the mare

The ending -o often suggests a masculine noun, and cavalo is masculine.

Bebe is the verb beber (to drink) conjugated for he/she/it and also you in formal speech (você).

So in this sentence:

• o cavalo bebe = the horse drinks

It is the 3rd person singular form.

Portuguese usually does not need a separate subject pronoun when the subject is already stated.

Here, the subject is o cavalo, so adding ele would be unnecessary in most normal contexts.

• O cavalo bebe água. = natural
• O cavalo, ele bebe água. = possible in some emphatic or spoken contexts, but not the neutral basic version

English needs it drinks, but Portuguese can simply say the horse drinks.

Yes. This sentence follows the common Subject + Verb + Object order:

• O cavalo = subject
• bebe = verb
• água = object

So it matches English very closely:

• The horse drinks water.

Portuguese can sometimes change word order for emphasis or style, but this basic order is the most common.

Because Portuguese, like English, can use a noun without an article when talking about something in a general or uncountable way.

Here:

• água = water

So:

• bebe água = drinks water

You could also hear bebe a água in a different context, but that usually points to a specific water, for example water already mentioned or present in the situation.

Compare:

• O cavalo bebe água. = The horse drinks water. / The horse drinks water in general.
• O cavalo bebe a água. = The horse drinks the water. / a specific water

Because água is a feminine noun.

So normally it takes feminine articles and adjectives:

• a água
• esta água
• água fria

Even though it starts with a stressed a sound, it is still feminine. In Portuguese, some feminine nouns beginning with stressed a use a in writing, and the pronunciation may sound like the two a sounds blend together:

• a água

So the gender is feminine, even if the sound pattern may feel unusual to an English speaker.

The accent mark in água shows the stressed syllable.

• á-gua

The stress falls on the first syllable: Água.

It also helps distinguish the pronunciation and spelling. In Brazilian Portuguese, água is pronounced roughly like AH-gwah, though the exact sound is more Portuguese than English.

A rough English-friendly pronunciation is:

• o cavalo bebe água
• oo kah-VAH-lo BEH-be AH-gwah

A few pronunciation notes:

• o often sounds like oo at the end of a phrase or in unstressed position
• cavalo has stress on va: ca-VA-lo
• bebe has stress on the first be: BE-be
• água has stress on á

This is only an approximation; Brazilian Portuguese vowel quality is different from English.

Because Portuguese spelling is not read the same way as English spelling.

In bebe:

• both b sounds are normal b
• the e vowels are short and clear, not like English bee-bee

In Brazilian Portuguese, bebe is approximately:

• BEH-bee or BEH-beh, depending on accent and phonetic detail

The important point is that the stress is on the first syllable: BE-be.

It can also mean you drink when you is você.

Examples:

• O cavalo bebe água. = The horse drinks water.
• Você bebe água. = You drink water.

That is because você takes the same verb form as ele/ela in Portuguese.

Yes, depending on context.

In Portuguese, the simple present can express:

• a general fact or habit: The horse drinks water
• sometimes a present action, especially in simple statements

However, if you specifically want to emphasize an action happening right now, Brazilian Portuguese very often uses:

• O cavalo está bebendo água. = The horse is drinking water.

So O cavalo bebe água most naturally feels like a general statement, but context matters.

Usually, in a normal standalone sentence, O cavalo bebe água sounds better and more natural.

If you say Cavalo bebe água, it can sound like:

• a headline
• a dictionary-style example
• a very general or reduced statement
• non-native speech in some contexts

For everyday standard speech, keeping o is the safest choice.

Cavalo is singular: horse.

The plural is cavalos: horses.

So:

• O cavalo bebe água. = The horse drinks water.
• Os cavalos bebem água. = The horses drink water.

Notice both the article and the verb change:

• o → os
• bebe → bebem

Beber ends in -er, so it is an -er verb.

Its present tense forms are:

• eu bebo = I drink
• você/ele/ela bebe = you/he/she drinks
• nós bebemos = we drink
• vocês/eles/elas bebem = you/they drink

So bebe fits the normal -er conjugation pattern.

Yes, it is a perfectly normal grammatical sentence, though in real life it depends on context.

It could be used:

• in a textbook
• to describe an animal
• in a child’s book
• when stating a simple fact

It sounds basic and natural. It is also a very common type of beginner sentence because the grammar is straightforward.