Learn Hardcore German: Meine Schwester übernimmt morgen die Führung des Projekts, was mich freut. - My sister will take over the leadership of the project tomorrow, which makes me happy.

Because übernehmen is an inseparable verb (the prefix über- is unstressed here), so the prefix never splits off. The correct 3rd person singular present is übernimmt, not nimmt … über.

Can the German present tense übernimmt refer to the future?

Yes. German often uses the present for scheduled or near-future events, especially with a time adverb like morgen. You could also say wird … übernehmen, but the present is natural: Meine Schwester übernimmt morgen …

What does was refer to in …, was mich freut?

Was refers to the entire preceding statement (the fact that she will take over). It’s a clause-level reference: “which (fact) pleases me.”

Could I use das or welches instead of was?

Not here. When referring to a whole clause or an indefinite antecedent, standard German uses was. Das would be non-standard in this function, and welches needs a specific neuter noun as its antecedent.

Why is it was mich freut and not was freut mich?

Because it’s a relative (subordinate) clause, and in German subordinate clauses the finite verb goes to the end: …, was mich freut. Was freut mich? is a direct question.

Why mich (accusative) and not mir (dative) with freut?

Because freuen in Es freut mich takes an accusative object. Compare: Es gefällt mir (dative) with gefallen, but Es freut mich (accusative) with freuen.

What’s the function of the comma before was?

It separates the main clause from the relative clause. Commas are mandatory before subordinate clauses in German.

What case is die Führung des Projekts, and why?

Genitive. Die Führung is specified by a genitive attribute: die Führung des Projekts (“the project’s leadership”). Die Führung von dem Projekt is possible but more colloquial; the genitive is preferred in formal style.

Why des Projekts and not des Projekt?

Masculine and neuter nouns in the genitive singular usually add -s or -es. das Projekt → des Projekts. The article changes to des and the noun adds -s.

Is des Projektes also correct?

Yes. Both des Projekts and des Projektes are standard. Today, the shorter -s ending is more common.

Can I move morgen to a different position?

Yes. Common options include:

Morgen übernimmt meine Schwester die Führung des Projekts, was mich freut.
Meine Schwester übernimmt die Führung des Projekts morgen, was mich freut. All are grammatical; word order affects emphasis.

Is there a difference between morgen and am Morgen?

Yes. morgen (lowercase) = “tomorrow.” am Morgen = “in the morning.” The noun der Morgen (capitalized) means “morning.”

Why meine Schwester and not meiner Schwester?

Meine Schwester is nominative (subject) feminine singular. Meiner Schwester would be dative or genitive and isn’t correct here.

Could I say die Projektleitung instead of die Führung des Projekts?

Yes. Die Projektleitung übernehmen is very common. Führung highlights leadership/command; Leitung leans toward management/administration. In many contexts, they overlap.

Does Führung also mean a “guided tour”? Is there ambiguity here?

Eine Führung can mean a guided tour, but with a genitive like die Führung des Projekts it clearly means leadership/management, so no ambiguity in this sentence.

How is übernehmen conjugated, and what are the key forms?

Present: ich übernehme, du übernimmst, er/sie/es übernimmt, wir übernehmen, ihr übernehmt, sie übernehmen
Simple past: ich übernahm …
Past participle: übernommen

Could I use worüber ich mich freue or worauf ich mich freue instead of was mich freut?

Yes, both are possible with the reflexive verb sich freuen:

…, worüber ich mich freue = what I am happy about (general/about a result)
…, worauf ich mich freue = what I’m looking forward to (future event) Here, since it’s about tomorrow, …, worauf ich mich freue fits well. Was mich freut (non‑reflexive, transitive) is shorter and neutral.