Когда на столе есть укроп и петрушка, ужин кажется вкуснее и красивее.

That is a very common question.

Russian normally does omit the present-tense verb to be in simple statements like:

• Он студент = He is a student
• Ужин вкусный = Dinner is tasty

But есть in this sentence does not just mean plain is. Here it has an existential meaning: there is / there are, or is present / exists.

So:

• на столе есть укроп и петрушка = there is dill and parsley on the table

Without есть, the sentence can still be understandable in some contexts, but есть makes the idea of presence/existence clear and natural.

So in this sentence, есть is being used because the meaning is roughly:

• When there is dill and parsley on the table...

Because на столе expresses location: on the table.

Russian uses different cases after prepositions depending on meaning. With на:

• на стол = onto the table or to the table surface
  This shows motion toward something.
• на столе = on the table
  This shows location.

In the sentence, nothing is moving. The dill and parsley are simply located there. So Russian uses the prepositional case:

• стол → на столе

Столе is the prepositional case singular of стол.

The preposition на often takes the prepositional case when it means on / at in the sense of location.

So:

• стол = nominative dictionary form
• на столе = on the table

This is one of the basic location patterns in Russian:

• в доме = in the house
• на улице = on the street
• на столе = on the table

Here they are the things that exist / are present, so they stay in the nominative case.

In a sentence like:

• На столе есть укроп и петрушка

the structure is basically:

• On the table there are dill and parsley

The things that exist are:

• укроп
• петрушка

So they appear in nominative.

This is different from some negative sentences, where Russian often uses the genitive:

• На столе нет укропа и петрушки = There is no dill or parsley on the table

So:

• affirmative existence: often nominative
• negative absence with нет: often genitive

Because the sentence begins with a subordinate clause introduced by когда.

Structure:

• Когда на столе есть укроп и петрушка, = subordinate clause
• ужин кажется вкуснее и красивее. = main clause

Russian punctuation requires a comma between the subordinate clause and the main clause.

This is similar to English punctuation in:

• When there is dill and parsley on the table, dinner seems tastier and prettier.

If the order were reversed, the comma would still be used:

• Ужин кажется вкуснее и красивее, когда на столе есть укроп и петрушка.

Here когда means when.

It introduces a clause describing the situation in which something happens or seems true:

• Когда на столе есть укроп и петрушка...
  = When there is dill and parsley on the table...

Depending on context, когда can sometimes refer to:

• a specific time: when
• repeated situations: whenever / when

In this sentence, it feels general:

• Whenever there is dill and parsley on the table, dinner seems tastier and prettier.

Because ужин is the subject of кажется.

The main clause is:

• ужин кажется вкуснее и красивее

This means:

• dinner seems tastier and prettier

So ужин is the thing that seems a certain way. That makes it the grammatical subject, and subjects are usually in the nominative case.

Кажется means seems / appears.

In this sentence:

• ужин кажется вкуснее и красивее
• literally: dinner seems tastier and prettier

The verb казаться often works with:

1. a subject in the nominative
2. a description of how that subject seems

Examples:

• Он кажется усталым. = He seems tired.
• Дом кажется большим. = The house seems big.

You may also see:

• Мне кажется... = It seems to me... / I think...

But in your sentence, there is no мне. It is just a general statement about appearance:

• Dinner seems tastier and prettier.

Because вкуснее and красивее are the normal comparative forms of the adjectives:

• вкусный = tasty
• красивый = beautiful / pretty

Comparative forms often mean:

• more tasty → tastier
• more beautiful → prettier / more beautiful

So:

• вкуснее = tastier
• красивее = prettier / more beautiful

Russian has two common ways to make comparatives:

1. simple comparative:
   
   • вкуснее, красивее
2. analytic comparative with более:
   
   • более вкусный, более красивый

The simple comparative is very common and natural here.

Because Russian comparative forms like вкуснее and красивее are generally invariable in this kind of use.

Unlike full adjectives such as:

• вкусный ужин
• вкусная еда
• вкусное блюдо

the comparative forms:

• вкуснее
• красивее

do not normally change for gender, number, or case.

So you can say:

• Ужин кажется вкуснее.
• Еда кажется вкуснее.
• Блюда кажутся вкуснее.

The comparative form itself stays the same.

It may sound slightly unusual in English, but in Russian it is perfectly understandable.

Красивее literally means more beautiful / prettier. With food, this often means:

• more visually appealing
• nicer-looking
• better-presented

So the sentence suggests that dill and parsley make dinner seem:

• вкуснее = tastier
• красивее = more attractive in appearance

A more natural English gloss might be:

• Dinner seems tastier and more appealing. or
• Dinner looks tastier and nicer.

But the Russian itself is fine.

Yes. Russian word order is flexible.

The given sentence is:

• Когда на столе есть укроп и петрушка, ужин кажется вкуснее и красивее.

You could also say:

• Ужин кажется вкуснее и красивее, когда на столе есть укроп и петрушка.

Both are grammatical. The difference is mainly in emphasis and flow.

The version with Когда... first sets up the condition or situation before giving the main point. That is very natural.

Russian word order often changes to highlight different information, but the case endings help show the grammatical roles.

You might hear something like:

• Когда на столе укроп и петрушка, ужин кажется вкуснее и красивее.

This is possible in conversational Russian, especially when the idea of presence is obvious from context. But it is a bit more elliptical.

With есть:

• Когда на столе есть укроп и петрушка... the sentence more clearly means:
• when there is dill and parsley on the table

So the version with есть is very natural and clear for this meaning.

Because Russian does not have articles.

English distinguishes between:

• a table
• the table

Russian simply says:

• стол

The exact meaning depends on context.

So:

• на столе can mean on the table
• ужин can mean dinner or the dinner
• укроп и петрушка can mean dill and parsley

In this sentence, context makes the meaning clear enough, so no article is needed.

In this sentence, укроп is being used as a mass noun, like dill in English.

Russian often uses plant names, herbs, and foods this way:

• укроп = dill
• петрушка = parsley

Even though they refer to herbs that may consist of many sprigs or leaves, the noun can still be singular because it refers to the substance or ingredient in general.

So:

• есть укроп и петрушка = there is dill and parsley

This is very similar to English mass-noun usage.

Because Russian can coordinate comparatives directly with и:

• вкуснее и красивее = tastier and prettier

Both words describe how the dinner seems. There is no need to repeat кажется or ужин.

This is just like English:

• Dinner seems tastier and prettier.

The two comparative words are parallel and naturally linked by и = and.