Cutia este sub grămadă.

Because cutie means box, while cutia means the box.

Romanian usually puts the definite article at the end of the noun instead of using a separate word like English the.

• cutie = box
• cutia = the box

So Cutia este... literally starts as The box is...

The definite article is attached to the noun as a suffix.

With cutie, the definite form becomes cutia. This is very normal in Romanian.

A rough breakdown is:

• cutie = box
• cutia = the box

For learners, the important thing is to memorize the definite form as part of the noun pattern, because the exact ending can vary depending on the noun’s gender and shape.

Este means is. It is the 3rd person singular form of a fi = to be.

So:

• Cutia este sub grămadă. = The box is under ...
• Cutia e sub grămadă. = same meaning, just more common in everyday speech

Both are correct.
Este sounds a little more full or formal; e is very common in conversation.

Sub means under or below.

In this sentence, it shows location:

• sub grămadă = under the pile / under a pile

It is a very common preposition for physical position.

Examples:

• sub masă = under the table
• sub pat = under the bed

This is a very natural question, because English speakers often expect a direct equivalent of the pile.

• grămadă = pile / heap
• grămada = the pile

So sub grămadă is a bare noun after a preposition. In Romanian, that can happen, and it may sound more general or less explicitly definite than English.

A useful way to think about it:

• sub grămadă = under a pile / under pile / under the heap, depending on context
• sub grămada = more clearly under the pile

So if you specifically mean one known pile, many learners will find sub grămada easier to understand as the more explicitly definite version.

Not necessarily.

• o grămadă = a pile
• grămadă by itself can appear after a preposition, especially in short, simple locational phrases

So these are different:

• sub o grămadă = under a pile
• sub grămadă = under pile / under a pile / under the heap, depending on context
• sub grămada = under the pile

Romanian does not always use articles in exactly the same places as English.

Yes. Sub normally takes the accusative.

In this sentence, though, you do not see a special visible case ending on grămadă, because many Romanian nouns look the same in the nominative and accusative.

So grammatically, it is accusative after sub, but the form itself does not change in an obvious way here.

A simple learner-friendly pronunciation is:

KOO-tee-ah ES-teh soob gruh-MAH-duh

A few details:

• cutia has three syllables: cu-ti-a
• sub sounds like soob
• grămadă has the vowel ă, which is like a soft uh sound, similar to the a in sofa

So grămadă is roughly:

gruh-MAH-duh

The stress is on ma.

The Romanian letter ă is usually pronounced like a neutral uh sound, similar to the vowel in the second syllable of English sofa.

So:

• gră ≈ gruh
• dă ≈ duh

That gives you:

gruh-MAH-duh

This sound is very common in Romanian, so it is worth getting used to early.

Yes, but the neutral, standard order here is:

Cutia este sub grămadă.

That is the most straightforward way to say The box is under ...

Romanian can sometimes move elements for emphasis, but as a learner, the safest pattern is:

subject + este/e + place

So this sentence is a good basic model.

Not always.

In this sentence, it is a physical pile / heap.

But grămadă is also very common in expressions like:

• o grămadă de oameni = a lot of people
• o grămadă de probleme = a lot of problems

So the word can mean either:

1. a literal pile/heap, or
2. a large amount of something

Here, it is the literal, physical meaning.

In a normal full sentence like this, no. You should keep it.

• Correct: Cutia este sub grămadă.
• Also correct and very common: Cutia e sub grămadă.

But simply saying Cutia sub grămadă would not be standard Romanian for this meaning.

So you may shorten este to e, but you normally do not omit the verb entirely.