Pompa de aer este lângă acvariu.

In Romanian, the definite article is usually attached to the end of the noun instead of being a separate word.

So:

• pompă = pump
• pompa = the pump

This is very common in Romanian. With many feminine nouns ending in -ă, the definite singular form changes that ending to -a:

• o pompă = a pump
• pompa = the pump

So Pompa de aer starts with the air pump, not just air pump.

De aer literally means of air, but in natural English we translate pompa de aer as air pump.

Romanian often uses this pattern:

• noun + de + noun

where English often uses a compound noun instead.

Examples:

• pompă de aer = air pump
• pompă de apă = water pump
• sticlă de vin = bottle of wine

Also, aer stays in its basic form here. Romanian does not need an article in this kind of expression.

In a sentence like this, Romanian normally keeps the verb to be.

• este = is

So:

• Pompa de aer este lângă acvariu. = The air pump is near the aquarium / an aquarium.

You normally would not omit este in standard Romanian.

In everyday speech, many people shorten este to e:

• Pompa de aer e lângă acvariu.

That is very common and natural.

Lângă usually means near, next to, or beside.

In this sentence it shows location, so it tells you where the pump is.

Depending on context, English could translate it as:

• near
• next to
• beside

So este lângă acvariu means the pump is positioned close to the aquarium.

This is a very useful article question.

• acvariu = aquarium or an aquarium
• acvariul = the aquarium

So if you want to be explicitly definite, you would normally use acvariul:

• Pompa de aer este lângă acvariul. = The air pump is next to the aquarium.

As written, acvariu is the unarticulated form. In learning materials, translations sometimes smooth this over depending on context, but the form difference is real and important to notice.

After lângă, Romanian uses the accusative case.

The helpful part for learners is that, with many nouns, the accusative looks the same as the basic dictionary form. That is why acvariu does not visibly change here.

So grammatically:

• lângă
  • accusative noun

But in practice, you often just see the normal noun form after the preposition.

These are two different Romanian vowels.

• â is a specifically Romanian sound. English does not have an exact match. It is a high central vowel, made with the tongue high in the middle of the mouth.
• ă is much easier for English speakers: it is close to the a sound in sofa.

So lângă is roughly:

• LUHN-guh

That is only an approximation, but it is a useful start.

A rough pronunciation guide is:

POM-pa de AH-er ES-te LUHN-guh ak-VAR-yoo

A few notes:

• pompa has stress on the first syllable
• aer has two syllables: a-er
• este is pronounced clearly as ES-te
• acvariu is roughly ak-VAR-yoo

A more Romanian-like pronunciation would be closer to:

• POM-pa de A-er ES-te LÂN-gă ak-VAR-yu

The given order is the most neutral and easiest for learners:

• Pompa de aer este lângă acvariu.

This is basically:

• subject + verb + location

Romanian word order can change for emphasis, but the basic version is the safest one to learn first.

For example, you might also hear a more marked order such as:

• Lângă acvariu este pompa de aer.

That puts more focus on the location. But for a normal, plain statement, the original order is best.

Yes, it matters, because gender affects articles and adjective agreement.

• pompă is feminine
• acvariu is neuter

Romanian neuter nouns behave:

• like masculine in the singular
• like feminine in the plural

That is why you may later see forms like:

• un acvariu = an aquarium
• două acvarii = two aquariums
• acvariul = the aquarium

For this sentence, the main thing to remember is:

• pompa is a feminine definite form
• acvariu is a neuter singular noun