Rețeaua electrică este stabilă.

In Romanian, the definite article is usually attached to the end of the noun, not written as a separate word like English the.

• rețea = network
• rețeaua = the network

So rețeaua electrică literally means the electrical network or the electric grid.

The final -a here is the definite article for this feminine singular noun.

Because adjectives in Romanian must agree with the noun they describe in gender, number, and definiteness/context.

Here, rețea is:

• feminine
• singular

So the adjective also takes the feminine singular form:

• masculine singular: electric
• feminine singular: electrică

That is why we get rețeaua electrică, not rețeaua electric.

For the same reason: stabilă is an adjective describing rețeaua, and it must agree with it.

Compare:

• un sistem stabil = a stable system
  (sistem is masculine/neuter singular in the singular pattern)
• o rețea stabilă = a stable network
  (rețea is feminine singular)

So in Rețeaua electrică este stabilă, both adjectives referring to rețeaua are feminine singular:

• electrică
• stabilă

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

So:

• este = is

In standard Romanian, you normally keep it in a sentence like this:

• Rețeaua electrică este stabilă.

In everyday speech, people very often use the shorter form e:

• Rețeaua electrică e stabilă.

But unlike in some languages, you do not usually drop the verb completely in a normal present-tense statement.

In Romanian, adjectives often come after the noun.

So:

• rețeaua electrică = the electrical network

This noun + adjective order is very common and natural in Romanian.

Sometimes an adjective can come before the noun, but that often gives a different style, emphasis, or literary tone. For a basic descriptive phrase, placing the adjective after the noun is the normal choice.

A rough pronunciation guide is:

• re-ȚEA-wa

A bit more carefully:

• ț sounds like ts in cats
• ea is pronounced together, somewhat like ya/ea
• ua also forms a glide-like sequence at the end

So rețea sounds roughly like re-TSE-a, and rețeaua sounds roughly like re-TSE-a-wa.

The exact Romanian pronunciation is smoother than English spelling suggests, but the important point for learners is that ț is always a ts sound.

These are Romanian diacritics, and they matter.

• ț = a ts sound
  Example here: rețea
• ă = a short central vowel, similar to the a in English sofa
  Example here: electrică, stabilă

If you leave out the diacritics, Romanians will usually still understand the word in context, but the correct spelling is:

• Rețeaua electrică este stabilă.

not

• Reteaua electrica este stabila

It is in the nominative case, because it is the subject of the sentence.

The structure is:

• Rețeaua electrică = subject
• este = verb
• stabilă = predicate adjective / subject complement

So this is a straightforward subject + verb + adjective sentence.

That would sound unnatural in normal Romanian.

The natural version is:

• Rețeaua electrică este stabilă.

Romanian word order is somewhat flexible, but not every rearrangement sounds normal. Putting electrică before rețeaua here is unusual and would sound marked, poetic, or just incorrect to many learners' ears.

If you want a standard sentence, keep:

• noun first: rețeaua
• adjective after it: electrică

The plural would be:

• Rețelele electrice sunt stabile.
• The electrical networks are stable.

Here is what changes:

• rețeaua → rețelele = the networks
• electrică → electrice = feminine plural adjective
• este → sunt = are
• stabilă → stabile = feminine plural adjective

This is a useful example of agreement across the whole sentence.

Yes, rețea is a feminine noun.

One clue is the singular article pattern:

• o rețea = a network
• rețeaua = the network

Also, the adjectives around it show feminine agreement:

• electrică
• stabilă

As a learner, one of the easiest ways to identify a Romanian noun’s gender is to look at how articles and adjectives behave with it, not just at the ending of the noun by itself.