Если дома нет укропа, я всё равно добавляю петрушку, потому что люблю свежую зелень.

Here дома means at home, not houses.

This is a very common adverb in Russian:

• Я дома = I am at home
• Мы остались дома = We stayed home

So Если дома нет укропа means If there is no dill at home.

A learner might expect something like в доме, but дома is the normal everyday way to say at home.

Because нет normally requires the genitive case.

So:

• nominative: укроп
• genitive: укропа

That is why you get:

• Есть укроп = There is dill
• Нет укропа = There is no dill

This is one of the most important patterns in Russian:

• нет времени = there is no time
• нет денег = there is no money
• нет сахара = there is no sugar

Because it is the direct object of добавляю (I add).

The basic verb pattern is:

• добавлять что? = to add what?

So:

• nominative: петрушка
• accusative: петрушку

Compare:

• Я люблю петрушку = I like parsley
• Я добавляю петрушку = I add parsley

Since петрушка is a feminine noun ending in -а, its accusative singular becomes -у.

Добавляю is the imperfective verb, and here it describes a habitual / repeated action:

• Если дома нет укропа, я всё равно добавляю петрушку
  = If there’s no dill at home, I still add parsley

This means that is what I generally do in that situation.

If you said добавлю, that would sound more like I will add on one specific future occasion.

So the contrast is:

• добавляю = I add / I usually add
• добавлю = I will add

Всё равно means anyway, all the same, or still.

In this sentence it shows that the speaker does not stop adding herbs just because dill is unavailable:

• Если дома нет укропа, я всё равно добавляю петрушку
• If there’s no dill at home, I still add parsley anyway

It is a very common expression:

• Я всё равно пойду = I’ll go anyway
• Он всё равно не согласится = He still won’t agree / He won’t agree anyway

Because Если дома нет укропа is a subordinate clause introduced by если (if).

Russian normally separates subordinate clauses with commas:

• Если будет время, я приду
• Когда он пришёл, мы уже ели
• Потому что устал, он лёг спать

So in your sentence:

• Если дома нет укропа, = subordinate clause
• я всё равно добавляю петрушку = main clause

Because потому что люблю свежую зелень is another subordinate clause, giving the reason.

• потому что = because

So the sentence structure is:

1. Если дома нет укропа = if-clause
2. я всё равно добавляю петрушку = main clause
3. потому что люблю свежую зелень = because-clause

Russian punctuation usually marks these clause boundaries with commas.

In this sentence, зелень means greens, fresh herbs, or leafy green plant ingredients used in food.

So свежая зелень means something like:

• fresh herbs
• fresh greens

It does not mean the color green here.

This word is often used collectively for herbs such as:

• укроп = dill
• петрушка = parsley
• кинза = cilantro/coriander
• зелёный лук = green onion

So люблю свежую зелень means I like fresh herbs/greens.

Because зелень is the object of люблю (I love/like), so it must be in the accusative case.

• nominative: свежая зелень
• accusative: свежую зелень

The adjective changes too:

• свежая → свежую

Compare:

• Свежая зелень полезна. = Fresh herbs are healthy.
  Here it is nominative, the subject.
• Я люблю свежую зелень. = I like fresh herbs.
  Here it is accusative, the object.

Russian often omits subject pronouns when they are clear from the verb form.

So:

• люблю already means I love / I like
• there is no need to say я люблю unless you want emphasis

In this sentence:

• потому что люблю свежую зелень = because I like fresh herbs

You could say потому что я люблю свежую зелень, but the pronoun is unnecessary unless you want extra emphasis or contrast.

Yes. Russian word order is more flexible than English, although the original version sounds very natural.

Original:

• Если дома нет укропа, я всё равно добавляю петрушку, потому что люблю свежую зелень.

You could also hear:

• Я всё равно добавляю петрушку, если дома нет укропа, потому что люблю свежую зелень.

Or for emphasis:

• Петрушку я всё равно добавляю, если дома нет укропа...

But the original order is clear and neutral:

1. condition first
2. main action
3. reason last

In Russian, любить can cover both to love and to like very much, depending on context.

With food and ingredients, it often means to like or to be fond of:

• Я люблю чай = I like/love tea
• Я люблю свежую зелень = I like fresh herbs

So in this sentence, translating it as I like fresh herbs is usually the most natural choice in English, even though the Russian verb is любить.

Russian has no articles like a, an, or the, and with food ingredients it often uses a bare noun.

So:

• нет укропа can mean there is no dill
• добавляю петрушку can mean I add parsley
• люблю свежую зелень can mean I like fresh herbs

Whether English needs some, the, or no article at all depends on the translation, but Russian usually leaves that unstated unless it needs to be specific.