En påmindelse i kalenderen hjælper mig, og en notifikation på mobilen minder mig om mødet.

Danish nouns have two grammatical genders:

• common gender → takes en
• neuter → takes et

In this sentence:

• en påmindelse
• en kalender
• en notifikation
• en mobil

but:

• et møde

That is why the definite form is mødet and not mødeen. You simply have to learn each noun with its gender.

In Danish, the definite article is usually attached to the end of the noun.

So:

• kalender = calendar

• kalenderen = the calendar

• mobil = mobile phone

• mobilen = the mobile phone

• møde = meeting
• mødet = the meeting

Very roughly:

• en/et + noun = a/an
• noun + -en/-et = the

This is one of the biggest structural differences from English.

This is a preposition choice that follows normal Danish usage.

• i kalenderen = in the calendar
  A reminder is thought of as being inside the calendar system.

• på mobilen = on the phone
  Notifications appear on a device or screen, so Danish often uses på.

It is not always purely literal. Like in English, prepositions often follow usage patterns that you learn together with the noun or context.

They express two different ideas:

• hjælper mig = helps me
• minder mig om mødet = reminds me about the meeting

So the first clause says the calendar reminder is useful or supportive in general.
The second clause says the phone notification specifically causes the speaker to remember the meeting.

Also note the verb pattern:

• at hjælpe nogen = to help someone
• at minde nogen om noget = to remind someone of/about something

Because the verb is at minde nogen om noget.

So:

• Den minder mig om mødet = It reminds me about the meeting.

The om is part of the normal pattern of the verb, just as English often says remind someone about/of something. It is best to learn minde together with this pattern, not as a single isolated word.

Because mig is the object form, while jeg is the subject form.

• jeg = I
• mig = me

In this sentence, the reminder and the notification are the subjects, and me is the object:

• En påmindelse ... hjælper mig
• En notifikation ... minder mig om mødet

So jeg would be wrong here.

That is the normal word order here.

In a simple Danish main clause with the subject first, the finite verb usually comes next, and the object comes after that:

• En påmindelse hjælper mig
• En notifikation minder mig om mødet

So the pattern is:

subject + verb + object

This is similar to normal English word order in these examples.

Because og is simply joining two main clauses, and the second clause starts with its subject:

• En påmindelse ... hjælper mig
• og en notifikation ... minder mig om mødet

That gives normal main-clause order:

subject + verb + ...

You would get inversion only if some other element came first. For example:

• På mobilen minder en notifikation mig om mødet

Here på mobilen comes first, so the verb moves into second position.

Yes, very possibly.

Danish often uses the definite form where English might prefer a possessive, especially when it is obvious whose thing is meant from the context.

So:

• i kalenderen can naturally mean in my calendar
• på mobilen can naturally mean on my phone

If you want to be more explicit or contrastive, you can say:

• i min kalender
• på min mobil

Both are possible, but the definite form alone is very natural when the context is clear.

Because this is a specific meeting, not just any meeting.

• et møde = a meeting
• mødet = the meeting

The sentence assumes that the speaker already knows which meeting is being talked about. That is why the definite form is used.

Not completely.

• påmindelse = reminder
• notifikation = notification

A påmindelse often focuses on the function: it helps you remember something.
A notifikation often sounds more technical or device-based: a phone alert, app alert, push notification, and so on.

In this sentence, the contrast is quite natural:

• a reminder in the calendar
• a notification on the phone

A phone notification can function as a reminder, but the words are not exact synonyms.

Yes. In modern Danish, mobil commonly means mobile phone.

So:

• en mobil = a mobile phone
• mobilen = the mobile phone

It is a normal everyday word, and often a shorter alternative to mobiltelefon.

Because the sentence contains two main clauses:

• En påmindelse i kalenderen hjælper mig
• en notifikation på mobilen minder mig om mødet

In standard Danish comma rules, you normally put a comma between main clauses, even when they are joined by og.

So the comma here is standard Danish punctuation.