Um discurso inacabado pode prejudicar a tua credibilidade, sobretudo se não souberes gerir bem o tempo.

Because inacabado is an adjective describing discurso, and discurso is masculine singular.

In Portuguese, adjectives usually agree with the noun they describe in gender and number:

• um discurso inacabado = a masculine singular noun
• uma apresentação inacabada = a feminine singular noun
• dois discursos inacabados = a masculine plural noun

So inacabado matches discurso.

Here inacabado means unfinished, incomplete, or left without a proper ending.

With discurso, it suggests that the speech does not reach a proper conclusion, or that it stops before the speaker has fully delivered it. It is not just about being short; it is about being not properly completed.

After poder, Portuguese normally uses the infinitive of the main verb:

• pode prejudicar
• pode ajudar
• pode melhorar

So pode prejudicar literally means can harm or may harm.

In this sentence, pode expresses possibility, not permission.

No. Prejudicar normally takes a direct object:

• prejudicar a tua credibilidade
• prejudicar os resultados
• prejudicar a imagem da empresa

The a in a tua credibilidade is not a preposition required by prejudicar. It is the definite article that goes with credibilidade.

Because in European Portuguese, possessives are very often used with a definite article:

• o meu livro
• a tua opinião
• a nossa casa

So a tua credibilidade is the normal European Portuguese structure.

This is one of the things that often feels strange to English speakers, because English says simply your credibility without an article.

Tua goes with tu, the informal singular way of saying you.

So the sentence is speaking directly to one person in an informal way.

Sua usually goes with você, which is more formal or more distant in European Portuguese. A more formal version would be:

Um discurso inacabado pode prejudicar a sua credibilidade, sobretudo se não souber gerir bem o tempo.

Also, sua can sometimes be ambiguous, since it can also mean his/her depending on context.

Because after se referring to a future or possible condition, Portuguese often uses the future subjunctive.

Here, souberes is the future subjunctive of saber for tu:

• eu souber
• tu souberes
• ele/ela/você souber

So se não souberes means if you do not know or if you fail to know how, in a future/conditional sense.

Compare:

• Se sabes a resposta... = if you know the answer... (general fact)
• Se souberes a resposta... = if you know the answer... (when the situation comes up / in the future)

Portuguese often leaves out the subject pronoun when the verb ending already makes the subject clear.

In souberes, the ending -es shows that the subject is tu. So se não souberes already means if you do not know.

You could say se tu não souberes, but it is not necessary.

Gerir means to manage. So gerir bem o tempo means to manage time well.

Also, saber + infinitive means to know how to do something:

• saber falar
• saber explicar
• saber gerir

So não souberes gerir bem o tempo means if you do not know how to manage time well.

In natural English, this often comes close to if you do not manage your time well.

Portuguese often leaves out a possessive when it is already obvious from the context.

Here, gerir bem o tempo naturally means manage your time well in a general sense. Adding teu is possible, but less neutral:

• gerir bem o tempo = manage time well
• gerir bem o teu tempo = manage your time well, with more emphasis on your

So the version in the sentence is the more natural general phrasing.

Sobretudo means especially, above all, or particularly.

It highlights the second part as an important case:

• An unfinished speech can harm your credibility,
• especially if you do not manage time well.

So it adds emphasis to the condition introduced by se.

The vocabulary is fairly formal or professional because of words like:

• discurso
• prejudicar
• credibilidade
• gerir

But the use of tua and the tu verb form makes it informal in address.

So overall, it sounds like fairly formal language used to speak directly and informally to one person.