Die Fahrkartenkopie liegt beim Erstattungsantrag.

Because German very often forms compound nouns by joining nouns together into a single word.

Here, Fahrkartenkopie is made from:

• Fahrkarte = ticket
• Kopie = copy

So German uses one combined noun where English would often say copy of the ticket.

The gender of a German compound noun is determined by its final part.

The last part here is Kopie, and Kopie is feminine: die Kopie.

So the whole compound is also feminine:

• die Fahrkartenkopie

This is a very important rule for German compounds.

That -n- is part of the form used when Fahrkarte appears inside a compound.

You can think of it as coming from Fahrkarten-, which looks like the plural form Fahrkarten. In many German compounds, the first noun appears in a linking form like this.

So:

• Fahrkarte → Fahrkartenkopie

This does not always need to be translated as an actual plural in English. It is just the standard compound form here.

It is in the nominative case because it is the subject of the sentence.

The subject is the thing that lies / is located / is attached.

So:

• Die Fahrkartenkopie = subject, nominative
• liegt = verb

Because the subject die Fahrkartenkopie is singular.

Even though die can also be a plural article in other sentences, here the noun is singular because Kopie is singular.

So the verb must also be singular:

• die Fahrkartenkopie liegt

If it were plural, you would have:

• die Fahrkartenkopien liegen

Literally, yes: liegen means to lie or to be lying.

But in sentences about papers, documents, or files, German often uses liegen in a broader sense, such as:

• is with
• is attached to
• is included with
• is on file with

So here it does not necessarily mean the copy is physically lying on top of the application. It can also mean that it is accompanying the application.

Beim is a contraction of:

• bei dem → beim

This is very common in German.

So:

• bei = a preposition
• dem = the dative form of der/das for certain nouns
• beim = shortened form of bei dem

Because bei always takes the dative case.

The noun Antrag is masculine:

• der Antrag

In the dative singular, der Antrag becomes:

• dem Antrag

So:

• bei dem Erstattungsantrag
• contracted: beim Erstattungsantrag

In this sentence, bei does not mean only physical location like next to.

With documents and administrative language, bei often means something like:

• with
• together with
• attached to
• included in / with

So beim Erstattungsantrag suggests that the ticket copy is with the reimbursement application, probably as an attachment or accompanying document.

It is another compound noun:

• Erstattung = reimbursement / refund
• Antrag = application / request

Together:

• Erstattungsantrag = reimbursement application / refund request

And again, the last part determines the gender:

• der Antrag
• therefore der Erstattungsantrag

Yes. German main clauses keep the finite verb in second position, but the first element can change.

So these are both possible:

• Die Fahrkartenkopie liegt beim Erstattungsantrag.
• Beim Erstattungsantrag liegt die Fahrkartenkopie.

The second version puts more focus on beim Erstattungsantrag.

Because all nouns are capitalized in German.

That includes simple nouns and compound nouns.

So both of these are capitalized because they are nouns:

• Fahrkartenkopie
• Erstattungsantrag