Im Sprachkurs erklärt die Dozentin, was ein Nomen und was ein Verb ist.

German main clauses usually put the finite verb in second position. The first position can be taken by many different elements, not just the subject.

Here, Im Sprachkurs is placed first for emphasis or topic:

• Im Sprachkurs erklärt die Dozentin, ...
• literally: In the language course explains the lecturer, ...

Because erklärt is the finite verb, it must stay in second position, so the subject die Dozentin comes after it.

If you started with the subject, that would also be correct:

• Die Dozentin erklärt im Sprachkurs, ...

Both are grammatical; the difference is mainly in emphasis.

Im is a contraction of in dem.

• in dem Sprachkurs → im Sprachkurs

Here it means something like in the language course or during the language class/course, depending on context.

German very often uses these contractions:

• im = in dem
• am = an dem
• zum = zu dem
• zur = zu der

Because this sentence expresses location, not movement.

German distinguishes:

• where? → usually dative
• where to? → usually accusative

So:

• im Sprachkurs = in the language course / in class → location
• in den Sprachkurs = into the language course → direction or movement

In this sentence, the lecturer is explaining something in the course, so the dative is used.

Dozentin means a female lecturer/instructor. It is the feminine form of Dozent.

• der Dozent = male lecturer
• die Dozentin = female lecturer

Here, die Dozentin is the subject of the sentence, so it is in the nominative case.

Because the sentence begins with Im Sprachkurs, that first element takes position 1. In a normal German main clause, the finite verb must be in position 2, so the subject comes after it.

Structure:

• Position 1: Im Sprachkurs
• Position 2: erklärt
• then: die Dozentin

This is often called inversion in English-language explanations of German word order.

Because the part after the comma is a subordinate clause—more specifically, an indirect question.

German normally separates subordinate clauses from the main clause with a comma.

Main clause:

• Im Sprachkurs erklärt die Dozentin

Subordinate clause:

• was ein Nomen und was ein Verb ist

So the comma is required.

Yes—here was does mean what, but in this sentence it introduces an indirect question:

• what a noun is
• what a verb is

German often uses was, wie, wo, warum, etc. to introduce indirect questions.

Compare:

• Direct question: Was ist ein Nomen?
• Indirect question: ..., was ein Nomen ist.

So was is not a relative pronoun here; it is the question word introducing an embedded question.

Because the clause after the comma is a subordinate clause, and in German subordinate clauses the finite verb usually goes to the end.

Compare:

• Main clause: Ein Nomen ist wichtig.
• Subordinate clause: ..., was ein Nomen ist.

That is one of the most important word-order patterns in German.

Because the sentence contains two coordinated indirect questions:

• was ein Nomen ist
• und was ein Verb ist

The first ist is omitted because it is understood from the second part. So the full version would be:

• ..., was ein Nomen ist und was ein Verb ist.

German often leaves out repeated material when it is obvious.

So the given sentence is a slightly more compact version of that fuller structure.

This is an example of ellipsis: German leaves out a repeated verb when it can be understood.

Full version:

• ..., was ein Nomen ist und was ein Verb ist.

Shorter version:

• ..., was ein Nomen und was ein Verb ist.

The second ist covers the structure, and the first one is understood. Learners often find the full version easier at first.

Because both nouns are singular and used in a general, classificatory sense:

• das Nomen
• das Verb

Both are neuter, so the nominative singular indefinite article is ein.

That is why you get:

• ein Nomen
• ein Verb

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

That is a basic rule of German spelling:

• der Sprachkurs
• die Dozentin
• das Nomen
• das Verb

This is very different from English, where common nouns are usually not capitalized.

Yes, absolutely. That version is very natural and may even be easier for learners to understand because it includes both instances of ist.

It differs from the original in two small ways:

1. Word order in the main clause

   • Original: Im Sprachkurs erklärt die Dozentin, ...
   • Alternative: Die Dozentin erklärt im Sprachkurs, ...

2. More explicit subordinate structure

   • Original: ..., was ein Nomen und was ein Verb ist
   • Alternative: ..., was ein Nomen ist und was ein Verb ist

Both are correct.

Yes.

• das Nomen = noun
• das Verb = verb

In German grammar, you may also see Substantiv for noun. In many contexts, Nomen and Substantiv are used similarly, though textbooks sometimes make small distinctions depending on grammar tradition. For a learner, Nomen = noun is the important point here.