Η μουστάρδα ταιριάζει με τη γαλοπούλα, αλλά η μαγιονέζα είναι καλύτερη με τις πατάτες.

Greek uses the definite article much more often than English. When Greek talks about foods or things in general, it often still uses the-type words, where English might use no article at all.

So Greek naturally says:

• η μουστάρδα = mustard
• τη γαλοπούλα = turkey
• τις πατάτες = potatoes

The article is also useful because it shows gender, number, and case.

These are different forms of the feminine definite article.

• η = nominative singular, used for the subject

  • η μουστάρδα
  • η μαγιονέζα

• τη(ν) = accusative singular

  • με τη γαλοπούλα

• τις = accusative plural

  • με τις πατάτες

After the preposition με, Greek uses the accusative, so the article changes form.

The full form is την, but in Modern Greek the final -ν is often dropped before many consonants. So τη γαλοπούλα is completely normal.

You will often learn the article as τη(ν), to show that both spellings/forms occur depending on what sound follows and on style.

Because Greek nouns have grammatical gender. A noun is masculine, feminine, or neuter, and that gender affects the article and adjective forms used with it.

Many nouns ending in -α are feminine, including these:

• η μουστάρδα
• η γαλοπούλα
• η μαγιονέζα
• η πατάτα

Then the plural of η πατάτα is οι πατάτες / τις πατάτες, but the noun is still feminine.

Ταιριάζει is the 3rd person singular present tense of ταιριάζω.

So:

• ταιριάζω = I match / I go well
• ταιριάζει = it matches / it goes well

It is singular because the subject is singular: η μουστάρδα.

Because the common pattern is ταιριάζω με + accusative, meaning go well with, match, or pair well with.

So:

• Η μουστάρδα ταιριάζει με τη γαλοπούλα = mustard goes well with turkey

This is something worth learning as a chunk: ταιριάζω με.

Because καλύτερη has to agree with η μαγιονέζα, which is feminine singular.

The comparative forms are:

• καλύτερος = masculine
• καλύτερη = feminine
• καλύτερο = neuter

So:

• η μαγιονέζα είναι καλύτερη

Even after είναι, adjectives still agree with the noun they describe.

Both are possible.

• καλύτερη = irregular comparative form
• πιο καλή = analytic comparative, literally more good

In this sentence, καλύτερη sounds very natural and idiomatic. Greek often prefers καλύτερος / καλύτερη / καλύτερο, but πιο καλή is also correct.

Because καλύτερη is a predicate adjective after είναι, not part of a noun phrase.

So Greek says:

• η μαγιονέζα είναι καλύτερη

not

• η μαγιονέζα είναι η καλύτερη

unless you specifically mean something like the best or the better one in a comparison.

No. Just like English, Greek uses the present tense for general truths, habits, and usual preferences.

So this sentence is not necessarily about one specific meal happening now. It is giving a general statement about what goes well with what.

Yes. Greek word order is more flexible than English because articles and endings already show a lot of grammatical information.

The sentence as written is a neutral, natural order:

• Η μουστάρδα ταιριάζει με τη γαλοπούλα
• η μαγιονέζα είναι καλύτερη με τις πατάτες

But for emphasis, Greek could move things around, for example:

• Με τις πατάτες, η μαγιονέζα είναι καλύτερη

That sounds more like With potatoes, mayonnaise is better.