Bir yandan çadırı temizledik, bir yandan eşyaları topladık.

In this sentence, bir yandan ... bir yandan ... means that two actions were happening alongside each other.

So the idea is:

• we cleaned the tent
• while also gathering/packing up the belongings

A natural English equivalent is often:

• while
• at the same time
• meanwhile

It is a very common Turkish pattern for parallel or simultaneous actions.

Not usually in a sentence like this.

Although the literal words may remind you of on the one hand ... on the other hand, here the meaning is not a contrast of opinions or alternatives. It shows simultaneous activity.

So this sentence is not saying:

• we did this instead of that
• or this versus that

It is saying:

• we were doing both things in parallel

It is repeated because Turkish often uses this paired structure to link two parallel actions:

• bir yandan X
• bir yandan Y

Repeating it makes the balance clear and sounds natural. It is similar to saying:

• partly X, partly Y
• while doing X, also doing Y

If you removed one of them, the sentence would sound less balanced and less idiomatic.

Because çadırı is the definite direct object form.

• çadır = tent
• çadırı = the tent

Turkish often uses the accusative ending on a direct object when that object is specific or definite.

Here, they cleaned a particular tent, so:

• çadırı temizledik = we cleaned the tent

If you said çadır temizledik, it would sound unnatural in this context.

Here, eşyaları most likely means the belongings or the things as a definite direct object.

Breakdown:

• eşya = thing / stuff / belongings
• eşyalar = things / belongings
• eşyaları = the things / the belongings (plural + accusative)

A useful note: eşyaları can also mean his/her belongings or their belongings in other contexts, because that form can be ambiguous in Turkish. But in this sentence, the most natural reading is simply:

• the belongings

They are both verbs in the simple past, 1st person plural (we).

• temizle-dik

  • temizle- = clean
  • -di- = past tense
  • -k = we
  • whole meaning: we cleaned

• topla-dık

  • topla- = gather / collect / pack up
  • -dı- = past tense
  • -k = we
  • whole meaning: we gathered / packed up

Because Turkish verb endings already show the person, you can tell that the subject is we even without the word biz.

Because Turkish often leaves out subject pronouns when the verb ending already makes the subject clear.

Here:

• temizledik = we cleaned
• topladık = we gathered / packed up

So biz is not necessary.

You could say Biz bir yandan çadırı temizledik..., but that would usually add emphasis, as if you especially want to stress we.

Because Turkish does not always need ve when two clauses are linked by a repeated structure like bir yandan ... bir yandan ....

The pairing itself already connects the two actions, so a comma is enough.

That makes this sentence natural:

• Bir yandan çadırı temizledik, bir yandan eşyaları topladık.

Adding ve would usually be unnecessary here.

It depends on context, but in this sentence topladık most naturally means something like:

• gathered up
• picked up
• packed up

The verb toplamak has a broad meaning: to gather, collect, pick up, bring together, tidy up.

With eşyalar (belongings / things), it often means:

• to gather the belongings
• to pack things up
• to pick things up

So if the scene is camping, eşyaları topladık probably means we packed up the belongings.

Not completely. Turkish word order is flexible, but this version is a very natural, neutral one.

Current order:

• Bir yandan çadırı temizledik, bir yandan eşyaları topladık.

This keeps:

• the parallel structure clear
• the verbs at the end of each clause, which is very typical in Turkish

You can move parts around for emphasis, but the meaning or focus may shift. For example, you might emphasize the objects differently in another order. Still, the given sentence is the most straightforward and natural way to say it.