L'experiència laboral és important.

Because l' is the shortened form of the definite article la or el before a vowel sound.

Here, the full form would be la experiència, but Catalan normally shortens it to l'experiència.

So:

• la experiència → l'experiència

In this sentence, the noun experiència is feminine, so the underlying article is la.

Catalan often uses the definite article with general or abstract nouns where English does not.

So L'experiència laboral és important sounds natural for a general statement meaning work experience is important.

Without the article, Experiència laboral would sound more like:

• a heading
• a label on a CV
• or an incomplete phrase rather than a full natural sentence

Yes, experiència is feminine singular.

You can tell mainly from the article:

• l' here stands for la
• so the noun is feminine

Also, many Catalan nouns ending in -ència are feminine.

So:

• la paciència
• la diferència
• l'experiència

Laboral means related to work, employment, or the workplace.

In experiència laboral, it works like an adjective describing what kind of experience:

• experiència = experience
• laboral = work-related

So experiència laboral means work experience or professional experience, depending on context.

In Catalan, adjectives often come after the noun, especially when they classify or define the type of thing.

So:

• experiència laboral = work experience
• literally, experience work-related

This is very normal in Catalan. English often puts this kind of modifier before the noun, but Catalan usually puts it after.

És is the verb to be in the third person singular:

• és = is

The accent matters because es without an accent is a different word, often a pronoun.

So:

• és important = is important
• es = a different grammatical word, not the verb form here

The accent helps distinguish them clearly in writing.

The accent in experiència shows where the stress goes and also indicates the vowel quality.

The stress falls on -èn-:

• ex-pe-ri-èn-ci-a

Without the accent, a learner might guess the stress incorrectly.

So the accent helps you pronounce the word properly.

No. In Catalan, many adjectives have the same form for masculine and feminine in the singular.

Important is one of those adjectives.

So you get:

• un tema important = an important topic
• una experiència important = an important experience

The adjective only clearly changes in the plural:

• important → importants

So in this sentence, important is already correct for feminine singular.

Yes, it does agree, but in this case the form does not change.

Both laboral and important are adjectives that can look the same in masculine and feminine singular.

So:

• experiència laboral
• situació laboral
• tema laboral

In the plural, you would see the change more clearly:

• experiències laborals
• coses importants

Because ser is used for general characteristics, definitions, or essential qualities.

This sentence is making a general statement:

• Work experience is important

That calls for ser:

• és important

Using estar here would not sound natural. Estar is usually used for states, conditions, locations, or temporary situations, not for this kind of general truth.

A careful approximate pronunciation for an English speaker is:

lehks-peh-ree-EN-see-uh loo-buh-RAL es eem-por-TANT

A few useful notes:

• x in experiència is pronounced like ks
• the stress in experiència is on èn
• és is stressed
• important is stressed on the last syllable

Depending on the dialect, the exact vowels may vary a bit, but that stress pattern is the key thing to notice.