A natureza muda com o tempo.

In Portuguese, it is very common to use the definite article with nouns, including abstract nouns and general concepts.

So a natureza means nature/nature in general.

English often drops the article in these cases, but Portuguese usually keeps it:

• A natureza é bela. = Nature is beautiful.
• A vida é curta. = Life is short.

So here, a natureza is the normal, natural form.

Here, muda is the verb mudar in the 3rd person singular present tense:

• eu mudo = I change
• tu mudas = you change
• ele/ela muda = he/she/it changes

Since the subject is a natureza (nature), Portuguese uses muda:

• A natureza muda = Nature changes

Be careful: muda can also be an adjective meaning mute in other contexts, but in this sentence it is clearly the verb.

Because the subject, a natureza, is grammatically singular.

Even though nature can refer to many things, Portuguese treats natureza as one singular noun, so the verb must also be singular:

• A natureza muda not
• A natureza mudam

This is the same idea as in English: Nature changes, not Nature change.

Com o tempo means with time, over time, or as time passes.

It is a very common expression in Portuguese. In this sentence, it tells us that the change happens gradually.

Examples:

• Com o tempo, tudo melhora. = With time, everything gets better.
• Com o tempo, aprendemos. = Over time, we learn.

So in your sentence, com o tempo means that nature changes gradually as time goes by.

Yes, tempo can mean both time and weather, depending on context.

Here it means time, because the expression com o tempo normally means with time / over time.

Compare:

• O tempo está bom. = The weather is good.
• Com o tempo, tudo muda. = With time, everything changes.

So the context tells you which meaning is intended.

Portuguese often uses the article where English would not.

So:

• com o tempo = literally with the time but naturally it means
• with time / over time

This is just normal Portuguese usage. You should learn com o tempo as a fixed expression.

Also note that com does not usually contract with the article in modern standard Portuguese:

• com o
• com a
• com os
• com as

Yes, muda is in the present indicative.

Portuguese, like English, often uses the present tense to express:

• general truths
• habits
• things that are generally true over time

So A natureza muda com o tempo means something like a general fact:

• Nature changes over time.

It is not only about what is happening right now at this exact moment.

Yes. Portuguese allows some flexibility.

You can also say:

• Com o tempo, a natureza muda.

This version is very natural and puts more emphasis on com o tempo.

Both versions are correct:

• A natureza muda com o tempo.
• Com o tempo, a natureza muda.

The basic meaning stays the same.

A rough European Portuguese pronunciation is:

a natuREza MUda com u TEMpu

More approximately:

• A sounds like a weak uh
• natureza has the stress on re
• muda has the stress on mu
• tempo has the stress on tem

A more technical approximation is:

/ɐ nɐtuˈɾezɐ ˈmuðɐ kõ u ˈtẽpu/

A few important European Portuguese points:

• unstressed vowels are often reduced
• d in muda may sound softer, a bit like th in some pronunciations
• com is nasal

Yes. A few natural alternatives are:

• A natureza altera-se com o tempo. = Nature changes over time.
• A natureza transforma-se com o tempo. = Nature transforms over time.
• A natureza muda ao longo do tempo. = Nature changes over the course of time.

These are all possible, but A natureza muda com o tempo is simple, natural, and very clear for everyday use.

Yes. Natureza is a feminine noun, which is why it uses:

• a natureza

This is something you need to memorize with the noun:

• a casa
• a cidade
• a natureza

The ending -a often suggests a feminine noun, though not always. In this case, natureza is indeed feminine.