Toto dílo je důležité.

Because dílo is a neuter noun, and the demonstrative must match its gender.

In the singular nominative:

• ten = masculine
• ta = feminine
• to / toto = neuter

So with dílo, you need the neuter form:

• to dílo = that / the work
• toto dílo = this work

Toto is a more explicit or slightly more formal way to say this.

Dílo is neuter.

A very common clue in Czech is that nouns ending in -o are often neuter:

• město = city
• auto = car
• dílo = work / piece of work

This matters because other words in the sentence must agree with it, including:

• the demonstrative: toto
• the adjective: důležité

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

In Toto dílo je důležité:

• toto dílo = the subject
• je = the verb is
• důležité = a predicate adjective describing the subject

So this is the basic subject + verb + description structure.

Because it agrees with dílo, which is neuter singular.

The adjective důležitý changes form depending on gender:

• masculine: důležitý
• feminine: důležitá
• neuter: důležité

So:

• ten muž je důležitý = that man is important
• ta kniha je důležitá = that book is important
• toto dílo je důležité = this work is important

Je is the 3rd person singular present form of the verb být = to be.

So:

• jsem = I am
• jsi = you are
• je = he/she/it is

Here it means is:

• Toto dílo je důležité. = This work is important.

Normally, no. In a regular sentence like this, you need je.

So:

• correct: Toto dílo je důležité.
• not standard as a full sentence: Toto dílo důležité.

You may sometimes see omission in titles, headlines, notes, or very informal style, but in normal grammar the verb to be stays.

Czech has no articles like English a/an/the.

So dílo can mean:

• a work
• the work
• simply work in context

The exact meaning depends on the situation, context, and words like toto.

Because the sentence has toto, the meaning is clearly specific:

• toto dílo = this work

Both are possible, but they are not exactly the same in feel.

• to dílo is very common and natural in everyday Czech
• toto dílo is more explicit, often a bit more formal, emphatic, or written-style

Very roughly:

• to can often function like that / the / this depending on context
• toto more clearly means this

So Toto dílo je důležité sounds perfectly correct, but in casual speech many speakers might also say To dílo je důležité or choose a different wording depending on context.

Not exactly.

Dílo usually means a work in the sense of a created piece, often something artistic, literary, or significant:

• a work of art
• a literary work
• a major created work

Práce more often means:

• work as labor
• a job
• an assignment
• a piece of work in a broader practical sense

So dílo in this sentence sounds more like a work / piece / creation, not just work in the general labor sense.

The neutral, standard order here is:

• Toto dílo je důležité.

Czech word order is more flexible than English, but changing it changes the emphasis.

For example:

• Toto dílo je důležité. = neutral statement
• Důležité je toto dílo. = emphasis on this work
• Je toto dílo důležité? = Is this work important?

So the sentence you have is the most basic and natural declarative order.

You negate je by changing it to není:

• Toto dílo není důležité. = This work is not important.

This is the standard way to negate sentences with být in the present tense.

A simple learner-friendly pronunciation is:

• důležité ≈ doo-leh-zhi-teh

A few useful points:

• ů is pronounced like a long ú sound, roughly oo
• ž sounds like the s in measure
• é is a long e

So the stress is on the first syllable, as usual in Czech:

• DŮ-le-ži-té

Because Czech relies heavily on agreement.

The noun dílo is neuter singular, so words connected to it must match:

• toto = neuter singular demonstrative
• důležité = neuter singular adjective

This agreement helps show relationships between words, which is one reason Czech can have freer word order than English.