Der Mülleimer in der Küche riecht schlecht, deshalb leere ich ihn jeden Abend.

Mülleimer is a masculine noun, so its basic dictionary form is der Mülleimer.

In this sentence, der Mülleimer is the subject of riecht:

• Der Mülleimer ... riecht schlecht.
• The trash can ... smells bad.

Subjects are in the nominative case, so we use der.

A quick comparison:

• der Mülleimer = nominative (subject)
• den Mülleimer = accusative (direct object)
• dem Mülleimer = dative

You can actually see the accusative later in the sentence indirectly through ihn, which refers back to der Mülleimer.

Because Küche is feminine, and here in is describing a location: the trash can is in the kitchen.

With two-way prepositions like in, German uses:

• dative for location: where?
• accusative for direction/movement: where to?

So:

• in der Küche = in the kitchen (location, dative)
• in die Küche = into the kitchen (movement, accusative)

Since the trash can is located there, not moving there, German uses the dative:

• der Küche

Because the subject is der Mülleimer, which is third person singular: it smells.

The infinitive is riechen = to smell.
When conjugated with der Mülleimer, it becomes:

• ich rieche
• du riechst
• er/sie/es riecht

So:

• Der Mülleimer riecht schlecht.

German verbs usually change form depending on the subject, just like English changes smell to smells.

Here schlecht means bad in the sense of smelling bad.

So:

• riecht schlecht = smells bad

This is a very normal German way to say that something has an unpleasant smell.

Schlimm usually means something more like:

• serious
• awful
• terrible
• bad in a more severe sense

For smells, schlecht riechen is the common expression.
You could also hear:

• stinkt = stinks

That is stronger and more direct than riecht schlecht.

Because deshalb is an adverb that takes up the first position in the clause, and in a normal German main clause the conjugated verb must come second.

So the structure is:

• Deshalb leere ich ihn jeden Abend.

Literally, German word order is something like:

• Therefore empty I it every evening.

This is a very important German rule: in a main clause, the finite verb is in position 2, not necessarily after the subject.

Compare:

• Ich leere ihn jeden Abend.
• Deshalb leere ich ihn jeden Abend.

Both are correct, but when deshalb comes first, the verb must come right after it.

All three can often mean therefore / that’s why / for that reason.

In everyday German:

• deshalb
• deswegen
• darum

are often very similar.

Examples:

• Der Mülleimer riecht schlecht, deshalb leere ich ihn jeden Abend.
• ..., deswegen leere ich ihn jeden Abend.
• ..., darum leere ich ihn jeden Abend.

They all sound natural here.

One useful point for learners: when these words begin a main clause, they usually trigger normal verb-second order:

• Deshalb leere ich ...
• Deswegen leere ich ...
• Darum leere ich ...

Leeren means to empty.

So:

• ich leere den Mülleimer = I empty the trash can

In the sentence, instead of repeating den Mülleimer, German uses the pronoun ihn:

• deshalb leere ich ihn
• therefore I empty it

Because Mülleimer is masculine, the accusative pronoun is:

• ihn = him/it

This may feel strange to English speakers because English uses it for objects, but German pronouns depend on grammatical gender:

• masculine: ihn
• feminine: sie
• neuter: es

Because ihn is the accusative form, and the trash can is the direct object of leere.

Compare:

• Er riecht schlecht. = It smells bad.
  Here the pronoun is the subject, so nominative er is used.
• Ich leere ihn. = I empty it.
  Here the pronoun is the object, so accusative ihn is used.

For masculine nouns:

• nominative: er
• accusative: ihn

Since Mülleimer is masculine, that is why the sentence uses ihn.

Jeden Abend is an accusative time expression meaning every evening.

German often uses the accusative without a preposition for expressions of time:

• jeden Tag = every day
• jede Woche = every week
• jeden Abend = every evening

Because Abend is masculine:

• nominative: jeder Abend
• accusative: jeden Abend

So in this sentence:

• ich leere ihn jeden Abend = I empty it every evening

Am Abend means in the evening or on the evening, which is different:

• Ich mache das am Abend. = I do that in the evening.
• Ich mache das jeden Abend. = I do that every evening.

It is one sentence with two main clauses joined by a comma and the connecting idea deshalb.

The two main ideas are:

1. Der Mülleimer in der Küche riecht schlecht
2. deshalb leere ich ihn jeden Abend

German often uses commas to separate clauses like this.

You could also write it as two shorter sentences:

• Der Mülleimer in der Küche riecht schlecht. Deshalb leere ich ihn jeden Abend.

That would also be correct.

In this sentence, the present tense does both jobs:

• it states a present fact: the trash can smells bad
• and it describes a habitual action: I empty it every evening

German uses the present tense very often where English also uses the present simple.

So:

• riecht schlecht = it smells bad
• leere ich ihn jeden Abend = I empty it every evening

If you wanted to make the habit even more explicit, German still usually keeps the present tense.

Not if you mean the trash can that is in the kitchen.

• in der Küche = in the kitchen / located in the kitchen
• aus der Küche = from the kitchen / coming from the kitchen

So:

• der Mülleimer in der Küche = the trash can in the kitchen
• der Mülleimer aus der Küche = the trash can from the kitchen

Those mean different things.

A useful breakdown is:

Der Mülleimer
subject

in der Küche
location

riecht
verb

schlecht
adverb/predicate description

, deshalb
connector meaning therefore

leere
verb in position 2 of the new clause

ich
subject

ihn
direct object

jeden Abend
time expression

So the pattern is roughly:

• [Subject] [place] [verb] [description], [connector] [verb] [subject] [object] [time]

This is very typical German:

• the first clause is a normal main clause
• the second clause begins with deshalb, so the verb comes immediately after it

Yes, it is part of the correct spelling and pronunciation.

• Mülleimer has ü
• It is not the same as u

The word is made from:

• Müll = garbage, trash
• Eimer = bucket, bin

So Mülleimer is literally something like garbage bucket/bin.

For learners, the important thing is:

• always write ü if possible
• if you cannot type it, ue is the standard replacement: Muelleimer

So:

• Mülleimer = correct normal spelling
• Muelleimer = acceptable substitute when umlauts are unavailable