Ich wechsle heute die Bettwäsche und wasche auch den Kissenbezug.

Because wechsle is the correctly conjugated form of the verb wechseln for ich in the present tense.

• wechseln = infinitive
• ich wechsle = I change
• du wechselst
• er/sie/es wechselt

So the sentence uses normal present-tense verb agreement: Ich wechsle ...

German very often uses the present tense for planned or expected future actions, especially when a time word makes the meaning clear.

So Ich wechsle heute ... can mean:

• I’m changing ... today
• or I’ll change ... today

You do not need a separate future form here. German would only use werden if the speaker wanted extra emphasis on the future.

In a normal German main clause, the conjugated verb usually comes in the second position. That is one of the most important word-order rules in German.

Here the order is:

• Ich = first element
• wechsle = verb in second position
• heute = time expression after the verb

So Ich wechsle heute ... is completely natural. You could also say Heute wechsle ich die Bettwäsche, and that would also be correct, but the emphasis would be slightly different because heute would be placed first.

This is about gender and case.

Both nouns are direct objects here, so they are in the accusative case. But their articles change according to gender:

• die Bettwäsche: feminine noun

  • nominative: die
  • accusative: die
    So the article stays the same.

• der Kissenbezug: masculine noun

  • nominative: der
  • accusative: den
    So the article changes from der to den.

That is why you see die Bettwäsche but den Kissenbezug.

Yes. In this sentence, both are direct objects, which means they are in the accusative case.

• Ich wechsle die Bettwäsche.
• (Ich) wasche den Kissenbezug.

A good way to spot this is to ask what?

• I change what? → die Bettwäsche
• I wash what? → den Kissenbezug

Yes. Bettwäsche is usually treated as a singular collective noun. It often refers to bed linen as a set, not to one single physical item.

So even if it includes several pieces, German commonly says:

• die Bettwäsche wechseln

This is similar to how English can use a mass or collective word like furniture or luggage. You normally would not use a regular plural here in everyday speech.

Because the subject is the same in both parts of the sentence, German can leave it out in the second coordinated clause.

So:

• Ich wechsle heute die Bettwäsche und wasche auch den Kissenbezug.

means the same as:

• Ich wechsle heute die Bettwäsche und ich wasche auch den Kissenbezug.

The shorter version is very natural and common. English does something similar sometimes: I change the bed linen and wash the pillowcase.

Auch means also or too. Here it shows that washing the pillowcase is an additional action.

In wasche auch den Kissenbezug, the most natural reading is:

• I change the bed linen, and I also wash the pillowcase.

Placing auch before den Kissenbezug makes that noun the main added item. Word order with auch can shift the focus slightly, so its position matters more than learners often expect.

German often builds long nouns by combining shorter ones. These are compound nouns:

• Bettwäsche = Bett
  • Wäsche
• Kissenbezug = Kissen
  • Bezug

The most important rule is that the last part determines the grammatical gender:

• die Wäsche → die Bettwäsche
• der Bezug → der Kissenbezug

This rule is very useful when learning German vocabulary.

Yes, that is grammatically correct. Repeating ich is not wrong.

The difference is mostly stylistic:

• without the second ich: smoother, more compact, more natural in many everyday contexts
• with the second ich: a bit more explicit, sometimes slightly more emphatic

So the original version sounds very normal, but both are possible.