O sexo é importante.

O is the masculine singular definite article, equivalent to the in English.

So:

• o sexo = sex

In Portuguese, it is very common to use the definite article with general nouns, especially when talking about a concept in a broad way. English often leaves out the in these cases, but Portuguese frequently includes it.

So O sexo é importante is a very natural way to say that sex, as a general concept, is important.

No. Grammatical gender and biological sex are different things.

Sexo is a masculine noun because Portuguese assigns it masculine grammatical gender, which is why it takes o:

• o sexo

This does not mean the word refers specifically to males. It is just the grammatical class of the noun.

Traditionally, sexo can refer to:

• sex in the biological sense
• sexual intercourse
• sometimes male/female category

In modern usage, though, gênero is often preferred when talking about gender in the social or identity-related sense.

So in this sentence, sexo would normally be understood as sex, not gender, unless context clearly suggests otherwise.

É is the 3rd person singular form of the verb ser, meaning is.

• eu sou = I am
• você é = you are
• ele/ela é = he/she is

The accent is important because:

• é = is
• e = and

So:

• O sexo é importante = Sex is important
• O sexo e importante would be incorrect, and it would also confuse is with and

Importante is an adjective with the same form for masculine and feminine singular.

So you can say:

• O sexo é importante
• A saúde é importante

In both cases, importante stays the same.

It only changes in the plural:

• importante = singular
• importantes = plural

Examples:

• O sexo é importante.
• As relações são importantes.

The structure is:

• O sexo = subject
• é = verb
• importante = predicate adjective

So it follows the very common pattern:

• subject + ser + adjective

Other examples:

• O trabalho é difícil.
• A vida é boa.
• Isso é normal.

This is very similar to English:

• Sex is important
• Work is difficult
• Life is good

A rough pronunciation for an English speaker is:

• o ≈ oo or a softer oh, depending on accent
• sexo ≈ SEH-shoo or SEH-ksoo, depending on region and speech style
• é ≈ eh
• importante ≈ eem-por-TAHN-chee

A rough full approximation might be:

oo SEH-shoo eh eem-por-TAHN-chee

A few notes:

• In much of Brazil, x in sexo often sounds like sh
• Final unstressed e often sounds like ee
• The stress in importante is on tan: im-por-TAN-te

Pronunciation varies by region, so small differences are normal.

Yes, it can.

Sexo is a normal word, but because it often refers directly to sexual intercourse, it can sound more explicit than English sex in some situations.

Depending on context, Brazilian Portuguese may use other expressions, such as:

• relação sexual = sexual intercourse
• vida sexual = sex life
• sexualidade = sexuality

Still, O sexo é importante is grammatically correct and completely understandable. Whether it sounds natural or blunt depends on the context and tone.

Yes, but it changes the feel slightly.

• O sexo é importante = more standard and complete when talking about the concept in general
• Sexo é importante = also possible, often more slogan-like, general, or headline-like

Portuguese often prefers the article in full statements like this, so O sexo é importante sounds especially natural in ordinary prose or speech.

Normally, no.

You use ser here because importante is being presented as an essential or general characteristic:

• O sexo é importante. = Sex is important.

Estar is usually used for states, conditions, or temporary situations. Saying O sexo está importante would sound unnatural in most contexts.

A helpful rule:

• ser = what something is like in a general or defining sense
• estar = how something is at the moment

So this sentence correctly uses ser.

In this sentence, importante is not directly modifying the noun inside the noun phrase. It comes after the verb é, so it works like important in Sex is important.

Compare:

• O sexo é importante. = Sex is important.
• o sexo importante = the important sex

These are different structures.

So here, importante comes after the verb because it is part of the predicate, not part of the noun phrase.

Grammatically, it is neutral and standard.

But because of the word sexo, the overall tone depends heavily on context:

• in a health, psychology, or relationship discussion, it sounds normal
• in casual conversation, it may sound direct or blunt
• in an academic or educational context, it is perfectly acceptable

So the grammar is neutral, but the topic itself may make the sentence feel stronger than a more everyday sentence like O trabalho é importante.

The verb and adjective would need to agree in number.

Singular:

• O sexo é importante.

Plural example:

• Os relacionamentos são importantes.

Changes:

• o → os
• é → são
• importante → importantes

So Portuguese shows plural agreement in both the verb and the adjective.