Θα έρθω ευχαρίστως.

Θα is the particle that usually marks the future in Modern Greek.

So:

• Θα έρθω = I will come

Greek does not form the future with a separate verb like will in English. Instead, it uses θα plus a verb form.

In this sentence, θα combines with έρθω to mean I will come or, more naturally here, I’ll gladly come / I’d be happy to come.

Because Greek uses a different verb form here.

• έρχομαι = I come / I am coming (present/imperfective)
• θα έρθω = I will come (future, with a perfective form)

The verb έρχομαι is irregular, so its future-related form is not built regularly from the present stem. Instead, Greek uses έρθω.

A very useful way to remember it is:

• έρχομαι = I come
• θα έρθω = I will come
• ήρθα = I came

So this is just one of the common irregular patterns you need to learn.

Not by itself.

έρθω is the form that appears after words like:

• θα for future
• να for subjunctive-type meanings
• sometimes after other particles or conjunctions

So:

• θα έρθω = I will come
• να έρθω; = Should I come? / Shall I come?

That means the future meaning comes from θα, not from έρθω alone.

Ευχαρίστως is an adverb meaning:

• gladly
• with pleasure
• happily

So Θα έρθω ευχαρίστως means something like:

• I’ll gladly come
• I’d be happy to come
• I will come with pleasure

It often sounds polite and willing, especially when accepting an invitation or suggestion.

Yes, it is natural and polite.

It sounds like a willing, positive response to an invitation, for example:

• Θες να έρθεις στο δείπνο;
• Θα έρθω ευχαρίστως.

In English, depending on context, you might translate it more naturally as:

• I’d be happy to come.
• I’d love to come.
• I’ll gladly come.

Greek word order is fairly flexible, and adverbs can often move around depending on emphasis.

In this sentence:

• Θα έρθω ευχαρίστως

the final position sounds very natural and gives ευχαρίστως a nice emphasis: I will come gladly.

You could also hear:

• Ευχαρίστως θα έρθω.

That puts more emphasis on the willingness itself, something like:

• Gladly, I’ll come.

Both are possible, but the original sentence is completely natural.

It is polite and a little more elevated than very casual speech, but it is still common and normal.

For example:

• ευχαρίστως = polite, pleasant, slightly more formal or careful
• In very casual speech, someone might instead say something like ναι, φυσικά or με χαρά

So Θα έρθω ευχαρίστως is not stiff, but it does sound courteous.

Yes, in English that can be a good translation depending on context.

Greek θα often corresponds to will, but English sometimes chooses would for a more natural tone, especially in polite situations.

So all of these can work depending on context:

• I will gladly come.
• I’d gladly come.
• I’d be happy to come.

If the sentence is a response to an invitation, I’d be happy to come is often the most natural English rendering.

A rough pronunciation is:

• tha ER-tho ef-ha-RI-stos

A slightly more accurate guide:

• Θα = tha as in a soft th sound
• έρθω = ER-tho
• ευχαρίστως = ef-ha-RI-stos

One useful point: ευ is pronounced either ev or ef depending on the following sound. Here it is ef, because the next consonant is voiceless:

• ευχαρίστως → efharístos

In Modern Greek, ευ changes pronunciation depending on the sound that follows.

• before a voiced sound, it is usually ev
• before a voiceless sound, it is usually ef

In ευχαρίστως, the next sound is χ, which is voiceless, so:

• ευχαρίστως → efharístos

This same pattern happens in many Greek words with ευ.

It is an adverb.

It tells you how the speaker will come:

• Θα έρθω = I will come
• Θα έρθω ευχαρίστως = I will come gladly

So it modifies the verb phrase, just like gladly does in English.

Yes, very often.

Ευχαρίστως can stand alone as a polite reply meaning:

• Gladly
• With pleasure
• Certainly

So if someone invites you somewhere, you might hear just:

• Ευχαρίστως.

The full sentence Θα έρθω ευχαρίστως is more explicit: I’ll gladly come.

Greek uses written stress marks, so the accent shows which syllable is stressed.

• έρθω is stressed on the first syllable: ER-tho
• ευχαρίστως is stressed on ρί: ef-ha-RI-stos

These accents are part of normal spelling in Modern Greek, so they are not optional in standard writing.