Στην ανηφόρα περπατάμε αργά, αλλά στην κατηφόρα πιο γρήγορα.

Στην is the contracted form of σε την.

• σε = in / on / at / to
• την = the for a feminine singular noun in the accusative

So:

• σε την ανηφόρα → στην ανηφόρα
• σε την κατηφόρα → στην κατηφόρα

In modern Greek, this contraction is the normal everyday form.

Because the preposition σε takes the accusative case in modern Greek.

Both ανηφόρα and κατηφόρα are feminine singular nouns. For many feminine nouns ending in -α, the nominative and accusative singular look the same in the noun itself.

So you get:

• η ανηφόρα = the uphill / the slope upward
• την ανηφόρα = the uphill / the slope upward, in the accusative

The change is mainly visible in the article:

• η → nominative
• την → accusative

They are very common Greek nouns:

• ανηφόρα = uphill, ascent, an upward slope
• κατηφόρα = downhill, descent, a downward slope

They can refer to:

• a sloping road
• a stretch of terrain
• the act or condition of going uphill/downhill

So στην ανηφόρα means something like on the uphill or when going uphill, and στην κατηφόρα means on the downhill or when going downhill.

Greek often uses the definite article in places where English may not.

So Greek says:

• στην ανηφόρα
• στην κατηφόρα

even where English might simply say:

• uphill
• downhill

This is very natural Greek. It does not always mean a specific single hill. It can also express a general situation: when on an uphill stretch / when on a downhill stretch.

Περπατάμε is the 1st person plural present active form of περπατάω / περπατώ, meaning to walk.

So περπατάμε means:

• we walk
• we are walking

depending on context.

In a sentence like this, it is usually understood as a general truth or habitual action:

• We walk slowly uphill, but faster downhill.

Greek present tense often covers both simple present and present progressive meanings.

Yes. Greek can use we in a broad, inclusive way, just like English sometimes does.

So περπατάμε can mean:

• we in the literal sense
• people generally / we humans / one

In this sentence, it sounds very natural as a general observation about how people walk on slopes.

Because Greek, like English, often omits repeated words when they are easy to understand from context.

The full version would be:

• Στην ανηφόρα περπατάμε αργά, αλλά στην κατηφόρα περπατάμε πιο γρήγορα.

But repeating περπατάμε is not necessary, so Greek usually leaves it out.

This kind of omission is very common and natural.

Here they are adverbs.

They describe how we walk:

• αργά = slowly
• γρήγορα = quickly

They come from the adjectives:

• αργός = slow
• γρήγορος = quick / fast

But in this sentence they are not describing a noun; they are modifying the verb περπατάμε, so they function as adverbs.

Yes, both are possible.

• πιο γρήγορα = more quickly / faster
• γρηγορότερα = faster / more quickly

The πιο + adverb/adjective pattern is extremely common in modern Greek and often feels very natural in everyday speech.

So this sentence could also be said as:

• Στην ανηφόρα περπατάμε αργά, αλλά στην κατηφόρα γρηγορότερα.

But πιο γρήγορα is very common and straightforward.

Because the contrast is built around the second part: downhill, faster.

The idea is:

• uphill: slow
• downhill: faster

Greek does not need to make both sides grammatically parallel. It is perfectly natural to state one side plainly and then compare the other side to it.

If you want a more explicitly balanced comparison, you could also say:

• Στην ανηφόρα περπατάμε πιο αργά, αλλά στην κατηφόρα πιο γρήγορα.

That would mean We walk more slowly uphill, but faster downhill.

So the original sentence is natural; it just presents the contrast a little asymmetrically.

Greek normally repeats the preposition and article in contrasting paired expressions like this.

So:

• στην ανηφόρα ... αλλά στην κατηφόρα ...

sounds complete and balanced.

If you removed the second στην, the sentence would sound unnatural or incomplete. Greek usually likes to restate the full phrase in this kind of contrast.

Because αλλά means but, and in standard Greek punctuation it is normally preceded by a comma when it links two contrasting parts of a sentence.

So:

• Στην ανηφόρα περπατάμε αργά, αλλά στην κατηφόρα πιο γρήγορα.

is standard punctuation.

This is very similar to English, where a comma often appears before but when two clauses or clearly contrasting parts are joined.

A rough pronunciation guide is:

STIN a-nee-FO-ra per-pa-TA-me ar-GHA, al-LA stin ka-tee-FO-ra pyo GHRI-gho-ra

A few stress points to notice:

• ανηφόρα
• περπατάμε
• αργά
• αλλά
• κατηφόρα
• πιο
• γρήγορα

Also:

• στην is pronounced as one word
• πιο is usually pronounced like pyo
• γ in γρήγορα is not a hard English g; it is a softer Greek sound