Det lyder godt, jeg kommer gerne.

Here det does not refer to a specific it in the usual concrete sense. It is a very common Danish dummy subject, like English it in It sounds good.

So:

• Det lyder godt = That/It sounds good

In this kind of sentence, Danish normally needs a subject, so det fills that role.

Lyder is the present tense of the verb at lyde (to sound).

• at lyde = infinitive
• lyder = present tense

So:

• Det lyder godt = It sounds good

This is similar to English sound becoming sounds with it.

Godt is the neuter singular form of the adjective god (good).

Danish adjectives often change form depending on the noun or pronoun they relate to. Since det is grammatically neuter, the adjective takes -t:

• en god idé
• et godt forslag
• det lyder godt

So in Det lyder godt, godt is the correct form because it matches det.

Not always. Literally, lyder godt means sounds good, but like English, it is often used more generally to mean:

• That seems good
• That sounds fine
• That works for me

So it can refer to an idea, plan, invitation, or suggestion, not just an actual sound.

Gerne means something like:

• gladly
• with pleasure
• happily

So:

• jeg kommer gerne = I’d be happy to come / I’ll gladly come

It adds a friendly, willing tone. Without gerne, jeg kommer is simply I’m coming or I will come. With gerne, it sounds more warm and enthusiastic.

Danish often uses gerne where English uses expressions like:

• I’d love to
• I’d be happy to
• I’d gladly

So jeg kommer gerne is very natural Danish for accepting an invitation.

You could also say:

• Jeg vil gerne komme = I would like to come / I’d like to come

That is also correct, but it is slightly different in focus.

• Jeg kommer gerne sounds like a direct, natural acceptance.
• Jeg vil gerne komme sounds more like expressing a wish or intention.

In many situations, both work.

Yes, the comma is natural here because there are two main clauses:

• Det lyder godt
• jeg kommer gerne

Each clause has its own subject and finite verb:

• det
  • lyder
• jeg
  • kommer

In English, you might more often separate this with a period or use and:

• That sounds good. I’ll gladly come.
• That sounds good, and I’ll gladly come.

In Danish, the comma is fine in this kind of short sentence.

Yes. That is completely natural.

The difference is mostly in rhythm and style:

• Det lyder godt, jeg kommer gerne.
  Feels a bit more connected and conversational.

• Det lyder godt. Jeg kommer gerne.
  Feels slightly more separated and clear.

Both are correct.

Grammatically, kommer is present tense, but Danish often uses the present tense to talk about the future when the meaning is clear.

So:

• jeg kommer gerne literally looks like I come gladly
• but in context it often means I’ll gladly come

This is very common in Danish.

A rough guide is:

• Det → something like deh or di depending on speech
• lyder → roughly LYU-thər or LYU-dər depending on accent and how carefully someone speaks
• godt → roughly goht
• jeg → often sounds closer to yai or yai
• kommer → roughly KOM-er
• gerne → roughly GAIR-nə or GEHR-nə

A more important point than exact spelling-based pronunciation is that Danish speech is often softer and more reduced than learners expect. For example, det and jeg are often pronounced in a reduced way in normal conversation.

It is neutral and natural, and it works well in everyday conversation. It is not especially formal, but it is also not slangy.

You could use it when replying to:

• an invitation
• a suggestion
• a plan

For example:

• Skal vi ses i morgen?
• Det lyder godt, jeg kommer gerne.

It sounds friendly and polite.