Experiența profesională este importantă.

Because Romanian usually adds the definite article to the end of the noun, instead of putting a separate word in front like English the.

• experiență = experience
• experiența = the experience

So experiența is the definite form of the noun.

For a feminine singular noun like experiență, the definite article is typically -a, but because of the spelling and sound changes, the result is experiența.

This is a very common thing in Romanian. Romanian often uses the definite form in general statements where English uses no article.

So:

• Experiența profesională este importantă.

can naturally mean:

• Professional experience is important.

Even though word-for-word it looks more like The professional experience is important, in normal Romanian this can still express a general idea.

This is something English speakers have to get used to: Romanian uses the definite article more often in abstract or generic statements than English does.

Because adjectives in Romanian must agree with the noun they describe in gender and number.

Here, experiență is:

• feminine
• singular

So the adjective must also be feminine singular:

• masculine singular: profesional
• feminine singular: profesională

That is why we get:

• experiență profesională
• experiența profesională

For the same reason: importantă agrees with the subject experiența profesională, which is feminine singular.

After the verb este, Romanian still makes the adjective agree with the noun:

• este important = if the subject is masculine singular
• este importantă = if the subject is feminine singular

So:

• Experiența profesională este importantă.

uses importantă because experiența is feminine singular.

Experiență is a feminine noun.

One clue is its ending: many Romanian nouns ending in -ă are feminine, although you should not rely on the ending alone 100% of the time.

A good way to confirm gender is to look at:

• the indefinite article:
  • o experiență = a/an experience
• the adjective agreement:
  • experiență profesională
  • experiența este importantă

Both show that the noun is feminine.

Because in Romanian, adjectives usually come after the noun.

So the normal order is:

• experiență profesională = professional experience

This is different from English, where adjectives usually come before the noun.

Romanian can sometimes place the adjective before the noun, but that is less neutral and can sound more literary, emphatic, or stylistically marked. For a basic learner, the safest pattern is:

• noun + adjective

When the adjective comes after the noun, the definiteness is usually shown only on the noun.

So:

• experiență profesională = professional experience
• experiența profesională = the professional experience / professional experience in a general sense

The adjective profesională stays in its normal agreeing form and does not need its own article here.

Romanian can also put an adjective before the noun in some cases, and then the form may look different, but in this sentence the standard structure is simply:

• experiența
  • profesională

In standard Romanian, yes, este is necessary.

• este = is

So:

• Experiența profesională este importantă.

needs the verb.

Unlike some languages, Romanian normally does not drop the present-tense verb to be in ordinary sentences like this. Leaving it out would sound incomplete or ungrammatical in standard usage.

A rough English-friendly guide is:

• Experiența ≈ eks-peh-ree-EN-tsa
• profesională ≈ pro-fe-see-o-NA-luh
• este ≈ YES-te
• importantă ≈ im-por-TAN-tuh

A few useful pronunciation points:

• ț is pronounced like ts in cats
• ă is a short central vowel, often approximated as uh
• Stress in experiența falls on -en-
• Stress in profesională falls on -na-
• Stress in importantă falls on -tan-

They are Romanian diacritics, and they matter for correct spelling and pronunciation.

• ț = the ts sound, like in cats
• ă = a short neutral vowel, often approximated by uh

So:

• experiența is not pronounced like English experience
• importantă ends with ă, not a full a sound

These marks are not optional in correct standard Romanian writing.

You may sometimes see it written without them online:

• Experienta profesionala este importanta.

People will still understand it, but it is not the correct standard spelling.

The proper form is:

• Experiența profesională este importantă.

As a learner, it is best to learn and use the diacritics from the start.

The difference is indefinite vs definite.

• experiență profesională = professional experience / a professional experience depending on context
• experiența profesională = the professional experience, or a general/generic idea in many contexts

In real Romanian, the definite form is often preferred in broad statements, which is why:

• Experiența profesională este importantă.

sounds natural.

But if you are just naming the concept, you might also see:

• Experiență profesională necesară = Professional experience required

So both forms exist; the choice depends on context.

To make it negative, add nu before este:

• Experiența profesională nu este importantă.
• Professional experience is not important.

To turn it into a yes/no question, Romanian often keeps the same word order and relies on intonation, or adds punctuation in writing:

• Experiența profesională este importantă?
• Is professional experience important?

So the basic pattern is:

• affirmative: este
• negative: nu este
• question: same sentence, but with question intonation or a question mark