Après le retard, je demande une compensation.

No. In French, retard is a normal, everyday noun meaning delay or lateness.

Examples:

• un retard de train = a train delay
• être en retard = to be late

So in this sentence, le retard means the delay.

Yes. Après literally means after.

So Après le retard means after the delay.

That said, if the idea is because of the delay or for the delay, French speakers might often prefer:

• À cause du retard = because of the delay
• Je demande une compensation pour le retard = I am asking for compensation for the delay

So the original sentence is understandable, but depending on the exact context, another wording may sound more natural.

In French, nouns usually need an article such as le, la, un, une, du, etc.

Here, le retard means the delay, usually a specific delay already known from the context.

French generally does not drop articles as often as English does, so Après retard would be incorrect.

Je demande is the present tense of the verb demander, meaning to ask or to request.

The infinitive is demander.
Its present-tense stem here is used like this:

• je demande = I ask / I am asking

So the sentence is using the first-person singular: I ask / I am asking.

It can cover both ideas, depending on the structure.

A very useful pattern is:

• demander quelque chose = to ask for something
• demander à quelqu’un = to ask someone
• demander quelque chose à quelqu’un = to ask someone for something

So:

• je demande une compensation = I ask for compensation / I request compensation

Unlike English, French does not need a separate word like for before the thing requested in this structure.

Une compensation means a compensation or some compensation.

It is indefinite: the speaker is asking for compensation, not referring to one specific compensation already identified.

If both speakers already knew exactly which compensation was being discussed, la compensation could be possible, but une compensation is the normal choice here.

You learn them with the article:

• le retard → masculine
• une / la compensation → feminine

So in this sentence:

• retard is masculine
• compensation is feminine

A helpful pattern: nouns ending in -tion are very often feminine in French, so compensation being feminine fits a common rule.

Yes. Je demande is present tense, so it means I ask or I am asking.

French present tense can be used for:

• something happening now
• a general statement
• a formal statement of action

If you wanted other times, you could change it:

• j’ai demandé une compensation = I asked for compensation
• je demanderai une compensation = I will ask for compensation
• je demande une compensation = I ask / I am asking for compensation

So the tense depends on when the request is happening.

Because Après le retard is an introductory phrase placed at the beginning of the sentence.

The comma helps separate that opening phrase from the main clause:

• Après le retard, je demande une compensation.

In short sentences, French punctuation can sometimes be flexible, and you may also see it without a comma. But with the comma, the sentence is clear and natural.