Hoje meus pés estão cansados porque eu caminhei muito.

Yes. Hoje means today, and putting it first is very natural because it sets the time right away.

So:

• Hoje meus pés estão cansados... = Today my feet are tired...

You could also say:

• Meus pés estão cansados hoje...

Both are correct. Starting with Hoje just sounds a little more like you are framing the whole statement around today.

In Brazilian Portuguese, both are possible:

• meus pés
• os meus pés

Both mean my feet.

Portuguese often allows the definite article before possessives, but it is not always required. In Brazil, omitting the article is very common in many contexts, especially in simple everyday sentences like this one.

So meus pés estão cansados sounds completely natural.

Pé means foot.
Pés means feet.

So:

• pé = foot
• pés = feet

The accent in pé and pés shows the stressed vowel sound. It helps distinguish pronunciation and is simply part of the correct spelling.

Because estar is used for a temporary condition, while ser is used for something more permanent or defining.

Here, tired is a temporary state:

• meus pés estão cansados = my feet are tired

If you used são, it would sound wrong in this context because being tired is not a permanent characteristic of your feet.

A useful shortcut:

• ser = to be, in an essential/permanent sense
• estar = to be, in a temporary/state sense

Because adjectives in Portuguese usually agree with the noun they describe in gender and number.

Here:

• pés is masculine plural
• so the adjective must also be masculine plural
• cansado → cansados

Compare:

• o pé cansado = the tired foot
• os pés cansados = the tired feet

If the noun were feminine plural, you would use -as, for example:

• as pernas cansadas = the tired legs

In this sentence, porque means because, so the one-word form is correct:

• ...porque eu caminhei muito. = ...because I walked a lot.

Portuguese has several similar-looking forms:

• porque = because
• por que = why / for what reason
• porquê = the reason
• por quê = why, usually at the end of a question

For this sentence, only porque fits.

Yes, it could.

Portuguese often drops subject pronouns when the verb form already makes the subject clear. Since caminhei clearly means I walked, you can say:

• porque eu caminhei muito
• porque caminhei muito

Both are correct.

Including eu can add emphasis, clarity, or simply reflect the speaker’s style. In Brazilian Portuguese, subject pronouns are often used more than in some other varieties, so eu caminhei sounds very natural.

Caminhei is the simple past (called the preterite in Portuguese) of caminhar.

It means:

• I walked

In this sentence, it refers to a completed action in the past:

• I walked a lot
• and now, as a result, my feet are tired

So the timeline is:

1. walking happened
2. feet are tired now

That is why the sentence combines:

• estão cansados = present
• caminhei = past

Because Hoje means today, and today can include time that has already passed.

For example, if you are speaking in the evening, you can say:

• Hoje eu caminhei muito. = Today I walked a lot.

Even though it happened earlier the same day, it is still natural to use the past tense because the walking is already completed.

Here, muito means a lot or a great deal, and it is acting as an adverb, modifying the verb caminhei.

• caminhei muito = I walked a lot

Because it is an adverb here, it does not agree with gender or number.

Compare:

• caminhei muito = I walked a lot
• muita caminhada = a lot of walking

In the second example, muita is an adjective/determiner modifying the feminine noun caminhada, so it changes form. But in your sentence, muito stays the same.

Yes, in many everyday situations you can.

• caminhei muito = I walked a lot
• andei muito = I walked a lot / I was on my feet a lot / I moved around a lot

Caminhar is more specifically to walk.
Andar is broader and can mean to walk, to go around, or to move about.

So caminhei muito is slightly more precise if you want to emphasize actual walking.

Yes, it is completely natural.

It sounds like a normal everyday sentence in Brazilian Portuguese. A Brazilian speaker would understand it immediately.

You may also hear similar variations, such as:

• Hoje estou com os pés cansados porque caminhei muito.
• Hoje meus pés estão cansados de tanto caminhar.

But the original sentence is clear and natural.

Estão is the plural form of está.

• está = is
• estão = are

The ending -ão is a very common nasal sound in Portuguese. In Brazilian Portuguese, it sounds roughly like owng but nasalized, not exactly like any normal English sound.

So:

• meus pés estão cansados = my feet are tired

It is plural because the subject pés is plural.

Because Portuguese prefers simpler, more natural structures here.

The sentence:

• Hoje meus pés estão cansados porque eu caminhei muito.

works well because:

• estão cansados expresses the current state
• caminhei muito gives the cause

A more literal English-style construction with tenho caminhado would usually sound less natural unless you specifically want to emphasize repeated or ongoing walking over a period of time.

So for a normal everyday statement, the original sentence is the best choice.