Legătura este importantă.

Because legătura is the definite form, meaning the connection / the link.

In Romanian, the definite article is usually attached to the end of the noun instead of appearing as a separate word like English the.

• legătură = a connection / connection
• legătura = the connection

So in this sentence, Legătura este importantă means The connection is important.

The basic form is legătură.

That is the singular indefinite form. In dictionaries, Romanian nouns are usually listed in this basic form, not with the attached definite article.

So:

• dictionary form: legătură
• definite singular: legătura

Because it has to agree with legătura, which is a feminine singular noun.

Romanian adjectives change form to match the noun in gender and number.

Here are the relevant forms of important:

• masculine singular: important
• feminine singular: importantă
• masculine plural: importanți
• feminine plural: importante

Since legătura is feminine singular, the correct form is importantă.

One clue is its ending: many Romanian nouns ending in -ă are feminine.

Also, the adjective confirms it:

• legătura este importantă → feminine singular adjective

A good habit is to learn Romanian nouns together with their gender, because adjective forms and articles depend on it.

Este is the 3rd person singular form of the verb a fi (to be).

So:

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she/it is

In Legătura este importantă, este means is.

Romanian usually uses the verb to be in this kind of sentence, just like English:

• The connection is important.

Yes. E is a very common short form of este.

So both are correct:

• Legătura este importantă.
• Legătura e importantă.

The version with e is more common in everyday speech, while este can sound slightly more formal or careful.

A simple learner-friendly pronunciation guide would be:

leh-guh-TOO-rah ES-teem por-TAHN-tuh

A few important points:

• ă is a short central vowel, similar to the a in English sofa
• tu in legătura is stressed: le-gă-TU-ra
• tan in importantă is stressed: im-por-TAN-tă

The letter ă appears twice here:

• legătură
• importantă

It does not sound like a full English a in cat or father.

The normal, neutral word order is:

Legătura este importantă.

That is:

• subject: Legătura
• verb: este
• adjective/complement: importantă

Romanian word order is fairly flexible, but this version is the most natural and standard.

You may sometimes see different orders for emphasis, but as a learner, this is the best pattern to use.

The indefinite version would use legătură instead of legătura.

For example:

• O legătură este importantă. = A connection is important.

Very often, Romanian may also omit o in some contexts, depending on style and meaning, but if you want to clearly say a connection, o legătură is the safest form.

So compare:

• Legătura este importantă. = The connection is important.
• O legătură este importantă. = A connection is important.

The plural would be:

Legăturile sunt importante. = The connections are important.

Breakdown:

• legăturile = the connections
• sunt = are
• importante = feminine plural form of important

So the changes are:

• singular legătura → plural legăturile
• singular este → plural sunt
• singular importantă → plural importante

Not necessarily. Legătură can be used in several ways, depending on context.

It can mean things like:

• a connection
• a link
• a relationship
• a tie
• a transport connection

So Legătura este importantă could refer to:

• a personal bond
• a logical connection
• a network link
• a transit connection

The exact nuance depends on the situation.