Learn Hardcore German: Die Musikerin am Klavier hilft ihr beim Üben und sagt, dass sie Talent hat. - The female musician at the piano helps her practise and says that she has talent.

auf dem Klavier = on top of the piano (physically on the surface)
beim Klavier (bei dem Klavier) = near the piano, by the piano (less idiomatic for playing)

For “a musician at the piano” (playing it), am Klavier is the natural phrase.

Why is it hilft ihr and not hilft sie?

Because helfen always takes a dative object, not an accusative one.

English: helps her → direct object
German: jemandem helfen (to help someone) → dative object

So we need the dative form of sie (she/her):

Nominative: sie (she)
Accusative: sie (her – direct object)
Dative: ihr (to her – indirect object)

Therefore:

Sie hilft ihr. = She helps her. (literally: She helps to her.)
In your sentence: …hilft ihr beim Üben… = …helps her with practicing…

Who does ihr refer to here?

ihr refers to a female person who is being helped – in your context, the learner / student.

We know:

Subject: Die Musikerin am Klavier (the female musician)
Verb: hilft
Dative pronoun: ihr = to her

So the musician (female) is helping another female person (the learner).
If the learner were male, you would see ihm instead of ihr:

Die Musikerin am Klavier hilft ihm beim Üben.

What does beim Üben mean, and why is Üben capitalized?

beim is a contraction of bei dem:

bei dem Üben → beim Üben

bei + dative can mean during / while / in the process of, so:

beim Üben ≈ while (she is) practicing / with her practicing

Üben here is a noun formed from the verb üben (to practice).
In German, when a verb is used as a noun (a “nominalized verb”), it is capitalized:

üben (to practice) → das Üben (the practicing)

That’s why Üben has a capital Ü.

Why is there a comma before dass?

Because dass introduces a subordinate clause, and in German you must put a comma before most subordinate clauses.

Structure of your sentence:

Main clause 1: Die Musikerin am Klavier hilft ihr beim Üben
- und (links two main predicates with the same subject)
Main clause 2 (continued subject): [Die Musikerin] sagt, …
Subordinate clause: dass sie Talent hat

The comma before dass separates:

the main clause (…sagt, …)
from
the subordinate “that”-clause (dass sie Talent hat)

What is the difference between dass and das?

dass (with ss) is a conjunction meaning that (introduces a subordinate clause):

Sie sagt, dass sie Talent hat.
= She says that she has talent.

das (with a single s) can be:

the article: das Klavier (the piano)
a demonstrative pronoun: Das ist gut. (That is good.)
a relative pronoun: Das Buch, das ich lese,… (The book that I am reading, …)

Rule of thumb:

If you can replace it with this/that/which in English → probably das
If you can replace it with that as a conjunction (She says that…) → dass

Why is the verb hat at the end of dass sie Talent hat?

Because in German, subordinate clauses (introduced by words like dass, weil, wenn, obwohl, etc.) normally send the conjugated verb to the end.

Pattern:

Main clause: Sie hat Talent. (verb in 2nd position)
Subordinate clause: …, dass sie Talent hat. (same words, but verb at the end)

So:

dass (conjunction)
sie (subject)
Talent (object)
hat (conjugated verb, final position)

Who does sie refer to in dass sie Talent hat — the musician or the learner?

Grammatically, sie could refer to either the musician or the person being helped; the pronoun itself is ambiguous.

In real usage, context decides:

In your likely context, sie refers to the learner (the person being helped), i.e. the musician says that the learner has talent.

To make it completely clear, German often repeats the noun or uses a more specific phrase:

…und sagt, dass die Schülerin Talent hat.
(…and says that the (female) student has talent.)
…und sagt, dass du Talent hast.
(…and says that you have talent.)

So: the sentence as given is understandable, but a bit ambiguous without additional context.

Why is it Talent haben and not something like ist talentiert?

Both exist, but they’re slightly different:

Talent haben = to have talent
Focuses on possessing an ability:
- Sie hat Talent. = She has talent.
talentiert sein = to be talented
More of an adjective describing a quality:
- Sie ist talentiert. = She is talented.

In your sentence:

…und sagt, dass sie Talent hat.
is the natural way to say …and says that she has talent.
You could also say:
…und sagt, dass sie sehr talentiert ist.
(…and says that she is very talented.) – slightly different nuance.

Could the word order be Die Musikerin hilft ihr am Klavier beim Üben? Does am Klavier have to come right after Musikerin?

You can move am Klavier, but the meaning shifts slightly.

Original:

Die Musikerin am Klavier hilft ihr beim Üben…
→ Emphasizes which musician: the one at the piano (as an identifying phrase).

Alternative:

Die Musikerin hilft ihr am Klavier beim Üben…
→ Now am Klavier sounds more like a description of where the helping happens (place of the action), not so much which musician.

Both are grammatically fine, but:

Die Musikerin am Klavier functions like a single noun phrase: the musician at the piano.
Putting am Klavier right after Musikerin therefore feels more natural if it’s defining which musician.

Why are words like Musikerin, Klavier, Üben, Talent all capitalized?

Because they are all nouns, and in German all nouns are capitalized.

die Musikerin – noun (person)
das Klavier – noun (thing)
das Üben – noun (nominalized verb)
das Talent – noun (abstract concept)

Even when a verb is turned into a noun (like üben → das Üben), it must be capitalized.