La tendo estas apud la dormosako.

Because -o is the normal noun ending in Esperanto.

• tendo = a tent
• dormosako = a sleeping bag

This is one of the most basic patterns in the language: if a word ends in -o, it is a noun.

La is the definite article, equivalent to English the.

It appears before both nouns because both are being talked about as specific things:

• la tendo = the tent
• la dormosako = the sleeping bag

Unlike English, Esperanto has just one form, la. It does not change for gender, number, or case.

Estas is the present-tense form of esti, meaning to be.

So it works like English is/are/am, but Esperanto uses the same form for every person:

• mi estas = I am
• vi estas = you are
• li estas = he is
• ili estas = they are

In this sentence, estas links the subject la tendo to the location phrase apud la dormosako.

Apud is a preposition meaning next to, beside, or by in a physical sense.

It usually suggests something fairly close, not just somewhere in the general area. So it is a good choice when one object is right beside another.

A rough contrast:

• apud = beside / right next to
• proksime de = near
• ĉe = at / by / with, often broader or less exact

Because this sentence describes a position, not movement.

Esperanto often uses -n for:

1. the direct object
2. direction toward somewhere

Here, apud la dormosako tells us where the tent is. It is a location phrase, so dormosako stays without -n.

Compare:

• La tendo estas apud la dormosako. = the tent is beside the sleeping bag
• Mi metas la tendon apud la dormosakon. = I put the tent next to the sleeping bag

In the second example, the phrase can show movement toward that position, so -n may appear.

Esperanto very often forms compound words by joining ideas together into a single word.

So dormosako is a compound:

• dormo = sleep
• sako = bag

Together, it means a bag for sleeping, that is, a sleeping bag.

This is very normal in Esperanto. The last part is usually the main idea, so dormosako is a kind of sako.

That -o- acts as a linking vowel in the compound.

Esperanto compounds are often built in a way that keeps them easy to say and understand. In many compounds, you will see this connecting -o- between parts:

• dormo-sako
• vapor-ŝipo or vaporoŝipo, depending on style and usage
• manĝoĉambro

In dormosako, the linking -o- makes the compound smooth and clear.

Usually, dormosako is the normal word.

Dorma sako would sound like a sleeping bag in the literal sense of a bag that is sleeping or a sleepy bag, which is not what you want.

Esperanto often prefers a compound noun when English uses a noun + noun structure:

• sleeping bag → dormosako
• not usually dorma sako

So for the object itself, dormosako is the standard choice.

Not completely. Esperanto word order is fairly flexible.

The most neutral order here is:

• La tendo estas apud la dormosako.

But you could also say:

• Apud la dormosako estas la tendo.

That version puts more focus on the location first, a bit like Beside the sleeping bag is the tent.

Even though word order can move around, the basic version is usually the safest choice for learners.

A simple pronunciation guide is:

la TEN-do ES-tas A-pud la dor-mo-SA-ko

A few useful points:

• Stress in Esperanto is always on the second-to-last syllable
• e is like e in bet
• o is like o in for but cleaner and shorter
• u is like oo in food
• Every letter is pronounced clearly

So the stress falls on:

• TEN in tendo
• ES in estas
• A in apud
• SA in dormosako

Sometimes, but it would not mean exactly the same thing.

• apud = physically beside, next to
• ĉe = at, by, with, in the vicinity of

So La tendo estas ĉe la dormosako would sound less precise, more like the tent is by the sleeping bag or at the sleeping bag's place.
Apud is better if you want to say the tent is specifically right next to it.