Ĉiufoje, kiam ŝi kudras la zipon, ŝi kontrolas la ŝtofon.

Ĉiufoje means every time or on each occasion.
Kiam means when.

Together, ĉiufoje, kiam ... is a very common pattern meaning every time when ... = whenever ... in natural English.

So:

• Ĉiufoje, kiam ŝi kudras la zipon, ...
• Every time she sews the zipper, ...
• or more naturally, Whenever she sews the zipper, ...

You usually need both parts because ĉiufoje sets up the idea of repetition, and kiam introduces the time clause.

The comma separates the main time expression from the clause introduced by kiam.

Esperanto often uses commas a bit more regularly than English, especially around subordinate clauses. In this sentence:

• Ĉiufoje, kiam ŝi kudras la zipon, ŝi kontrolas la ŝtofon.

the kiam clause is inserted between the opening time expression and the main clause, so commas help show the structure clearly.

A useful way to see it is:

• Ĉiufoje ... ŝi kontrolas la ŝtofon.
• kiam ŝi kudras la zipon = extra clause telling when

The ending -n marks the direct object in Esperanto.

Here:

• ŝi kudras la zipon = she sews the zipper
• ŝi kontrolas la ŝtofon = she checks the fabric

In both cases, the thing receiving the action gets -n:

• la zipo = the zipper

• la zipon = the zipper as direct object

• la ŝtofo = the fabric
• la ŝtofon = the fabric as direct object

This is one of the most important features of Esperanto grammar.

Esperanto normally states the subject explicitly in each clause unless the context makes omission possible in some special construction.

So:

• kiam ŝi kudras la zipon
• ŝi kontrolas la ŝtofon

Both clauses have their own subject, and Esperanto naturally repeats ŝi.

In English, we also usually repeat it:

• Every time she sews the zipper, she checks the fabric.

Leaving out the second ŝi would sound incomplete or ungrammatical in normal Esperanto.

Esperanto often uses the present tense for actions that happen regularly or habitually.

So this sentence is not about one specific sewing event. It means something like:

• Whenever she sews the zipper, she checks the fabric.
• Each time she sews the zipper, she checks the fabric.

This is a general repeated action, so the present tense is exactly what you would expect.

Yes, literally it means sews the zipper.

Depending on context, English might say:

• sews the zipper
• sews in the zipper
• attaches the zipper

Esperanto often leaves some things to context. If the meaning is specifically sew in / sew onto, speakers may still say kudri la zipon if the situation is clear.

If someone wanted to be more explicit, they might use a slightly fuller expression, but the sentence as given is perfectly understandable.

La means the.

Here it suggests that the speaker has a specific zipper and fabric in mind, probably in the context of a sewing task or garment construction:

• la zipon = the zipper
• la ŝtofon = the fabric

This is natural if both items are already known from context. For example, a seamstress is working on a particular project, so the zipper and the fabric are identifiable.

Without la, the meaning would be more general or indefinite:

• ŝi kudras zipon would sound like she sews a zipper / zipper material, which is less likely here.
• ŝi kontrolas ŝtofon would sound more like she checks fabric in a generic sense.

Yes. Ĉiufoje is built from:

• ĉiu = each, every
• foje = time, occasion; also -foje can be used in expressions about frequency or number of times

So ĉiufoje literally means each time or every time.

This is a useful pattern to recognize. Related forms include:

• unufoje = once, one time
• dufoje = twice, two times
• kelkfoje = sometimes, a few times
• multfoje = many times, often

Yes. You could say:

• Kiam ŝi kudras la zipon, ŝi kontrolas la ŝtofon.

This means when she sews the zipper, she checks the fabric.

However, that version can sound a little less explicitly repetitive.
Using Ĉiufoje, kiam ... makes the every time / whenever meaning especially clear.

So the original sentence emphasizes repetition more strongly.

Yes, Esperanto word order is fairly flexible, but this sentence uses a very normal and clear order.

The basic structure is:

• Ĉiufoje, kiam ŝi kudras la zipon, ŝi kontrolas la ŝtofon.

Because of the -n object ending, you can often move parts around without losing the meaning. But not every rearrangement sounds equally natural.

For learners, the given order is a very good standard pattern:

1. time expression
2. subordinate clause
3. main clause

It overlaps with both.

• ŝtofo usually means fabric, cloth, or textile material
• the best English translation depends on context

In a sewing context, fabric is often the most natural translation. So ŝi kontrolas la ŝtofon would usually be understood as she checks the fabric.

Yes. Kontroli usually means to check, inspect, verify, or examine.

So ŝi kontrolas la ŝtofon could mean she is:

• checking the fabric for mistakes
• inspecting it
• making sure it is positioned correctly
• verifying that nothing is wrong

The exact shade of meaning comes from the sewing context.

The main clause is:

• ŝi kontrolas la ŝtofon

The subordinate clause is:

• kiam ŝi kudras la zipon

A quick test: the subordinate clause begins with kiam, which introduces a time relationship. The main clause is the part that could stand on its own as a full sentence:

• Ŝi kontrolas la ŝtofon. = complete sentence

Meanwhile:

• kiam ŝi kudras la zipon = not complete by itself in this use; it needs the rest of the sentence

So the full meaning is: during each occurrence of the sewing action, the checking action happens.