O vale fica entre duas encostas.

In this sentence, ficar means something like to be situated / to lie / to be located.

So O vale fica entre duas encostas means the valley lies or is located between two slopes.

A quick comparison:

• ser = to be, for identity or permanent characteristics
• estar = to be, for states or conditions
• ficar = to be located, to remain, to become, depending on context

With places, ficar is very common in Portuguese:

• Lisboa fica no oeste de Portugal.
• A casa fica perto da praia.

So here, fica is the most natural choice.

Portuguese usually uses the definite article more often than English.

• O vale = the valley

In English, you might sometimes speak more generally without the, but in Portuguese the article often sounds more natural when referring to a specific thing or a typical example in context.

If you said just Vale, it would usually sound incomplete here.

Vale is a masculine noun meaning valley.

Important details:

• singular: o vale
• plural: os vales

Also, be aware that vale can also be a verb form of valer (it is worth / he, she, you are worth), but in this sentence it is clearly the noun valley because it comes after the article o.

Encosta usually means slope, hillside, or side of a hill/mountain.

So duas encostas means two slopes or two hillsides.

Depending on context, English could translate it in slightly different ways:

• slope
• hillside
• side of a hill

Here it helps describe the sides around the valley.

Because encosta is a feminine noun.

In Portuguese, numbers like one and two change for gender:

• masculine: dois
• feminine: duas

So:

• duas encostas = two slopes
• dois vales = two valleys

This is basic agreement:

• encostas is feminine plural
• so the number must also be feminine: duas

Because the sentence says the valley is between two slopes.

A valley is typically understood as being between one side and another side, so plural makes sense:

• encosta = slope
• encostas = slopes

If it were singular, the meaning would change and would sound strange in this context:

• entre uma encosta would mean between one slope, which does not really work logically.

Because duas encostas is an indefinite expression: two slopes, not the two slopes.

Compare:

• entre duas encostas = between two slopes
• entre as duas encostas = between the two slopes

So both are possible, but they mean slightly different things:

• duas encostas = any two slopes, not specifically identified
• as duas encostas = two specific slopes already known in the conversation

Entre means between or sometimes among, depending on context.

In this sentence:

• entre duas encostas = between two slopes

It is used very much like English between.

Other examples:

• entre Lisboa e Porto = between Lisbon and Porto
• entre amigos = among friends

So with two things, it usually matches English between very closely.

Yes, it is completely normal.

The structure is:

• O vale = subject
• fica = verb
• entre duas encostas = prepositional phrase showing location

So the order is:

subject + verb + place/location

That is a very standard Portuguese pattern.

In European Portuguese, it is approximately:

u VAL-uh FEE-kah EN-truh DWAHZH en-KOSH-tash

A few useful pronunciation notes:

• o often sounds like u when unstressed
• final -e in vale is reduced, something like uh
• entre is usually pronounced with a reduced final vowel
• duas encostas links smoothly in speech
• s at the end of duas sounds like zh before the vowel in encostas
• encostas has the stress on -cos-

A more phonetic approximation for European Portuguese would be:

u ˈvalɨ ˈfikɐ ˈẽtɾɨ ˈdwɐʒ ẽˈkɔʃtɐʃ

Yes, está entre duas encostas is possible and understandable, but fica entre duas encostas is more natural when describing location in a general way.

The difference is roughly:

• fica = is located / lies
• está = is

So:

• O vale fica entre duas encostas sounds more like a geographic description.
• O vale está entre duas encostas is not wrong, but it is a bit less idiomatic in this kind of statement.

For places and locations, Portuguese often prefers ficar.