Die Schublade klemmt wieder.

Because Schublade is a feminine noun in German, so in the nominative singular it takes die.

• die Schublade = the drawer
• plural: die Schubladen = the drawers

In this sentence, die Schublade is the subject, so the nominative form is used.

Here, klemmt means something like:

• is stuck
• is jammed
• won’t open/close properly

The verb is klemmen. Its basic idea is that something is being pinched, caught, or jammed.

So Die Schublade klemmt means the drawer is not moving smoothly because it is catching on something.

Because the subject is die Schublade, which is third person singular (it).

The verb klemmen is conjugated like this in the present tense:

• ich klemme
• du klemmst
• er/sie/es klemmt
• wir klemmen
• ihr klemmt
• sie/Sie klemmen

Since die Schublade = it, you use klemmt.

German main clauses usually follow the V2 rule: the finite verb goes in the second position.

So the structure is:

• Die Schublade = position 1
• klemmt = position 2
• wieder = the rest of the sentence

That is why Die Schublade wieder klemmt is not correct as a normal main clause.

Wieder means again.

So the sentence means:

• The drawer is jammed again.

It suggests this is a repeated problem, not something happening for the first time.

In a simple German statement, adverbs like wieder often come after the verb, especially when they modify the whole situation.

So:

• Die Schublade klemmt wieder. = natural

German often places this kind of time/repetition word later than English does.

You can also move wieder for emphasis:

• Wieder klemmt die Schublade. = Again, the drawer is jammed.

That sounds more emphatic or stylistically marked.

Not in normal English. Even though klemmen can sometimes relate to clamping, in this context with Schublade, the natural meaning is:

• The drawer is stuck again
• The drawer is jammed again

So you should understand klemmt here as describing a problem with movement.

No. That is incorrect.

Klemmen is a normal verb by itself, so you say:

• Die Schublade klemmt.

You do not add ist.

English often uses to be + adjective/past participle (is stuck), but German often uses a simple verb where English does not.

Here it is used intransitively.

• Die Schublade klemmt.
  = The drawer is jammed.

But klemmen can also be used transitively in other contexts:

• Ich klemme die Unterlagen unter den Arm.
  = I tuck the documents under my arm.

So the verb has more than one use. In this sentence, it simply describes the drawer’s condition.

A rough English-friendly guide:

• Schublade ≈ SHOO-blah-duh
• klemmt ≈ klemt

A few details:

• sch is pronounced like English sh
• the u in Schu- is a long oo sound
• -ade in Schublade is pronounced roughly ah-duh
• mmt at the end of klemmt is compact; the final t is pronounced

Normally, no. In standard German, countable singular nouns usually need an article or some other determiner.

So you would normally say:

• Die Schublade klemmt wieder.
• Meine Schublade klemmt wieder.
• Eine Schublade klemmt wieder.

Just Schublade klemmt wieder sounds incomplete in normal standard German.

Yes, very similar.

• Die Schublade klemmt wieder.
• Die Schublade steckt wieder fest.

Both can mean the drawer is stuck again.

A small nuance:

• klemmt focuses on jamming/catching
• steckt fest focuses on being stuck and unable to move

In everyday language, both are very natural.

You can make a yes/no question by putting the verb first:

• Klemmt die Schublade wieder?
  = Is the drawer jammed again?

That is a very common German pattern:

• statement: Die Schublade klemmt wieder.
• question: Klemmt die Schublade wieder?

The plural is:

• Die Schubladen klemmen wieder.
  = The drawers are jammed again.

Notice the changes:

• singular: die Schublade
• plural: die Schubladen
• singular verb: klemmt
• plural verb: klemmen