La cinta de equipajes está junto a la báscula.

Because Spanish normally uses estar for the physical location of people and things.

• La cinta ... está junto a la báscula = the belt is next to the scale.
• El mostrador está allí = the counter is over there.

By contrast, ser is usually not used for where an object is located. A useful exception is with events:

• La reunión es en la sala 2 = the meeting is in room 2.

So for an airport object like la cinta, está is the natural choice.

Junto a means next to, beside, or right by.

It is very close in meaning to al lado de, and in many situations they are interchangeable:

• La cinta está junto a la báscula
• La cinta está al lado de la báscula

Both sound natural.

A small nuance:

• junto a can sound a little more formal or written
• al lado de is very common in everyday speech
• cerca de means near, so it is less exact than next to

So if the objects are immediately beside each other, junto a works very well.

Because both cinta and báscula are feminine singular nouns.

In Spanish, nouns normally need an article much more often than in English. So where English says the belt and the scale, Spanish says la cinta and la báscula.

Here:

• la cinta = feminine singular
• la báscula = feminine singular

This is just part of normal Spanish noun grammar: article + noun must agree in gender and number.

Spanish often uses the pattern noun + de + noun where English uses a compound noun.

So:

• baggage belt → cinta de equipajes
• coffee cup → taza de café
• train station → estación de tren

This is one of the most common structural differences between English and Spanish. English likes stacking nouns together; Spanish usually links them with de.

Because equipajes is being used in a general, category-type way: it describes what kind of belt it is.

So cinta de equipajes means something like:

• a belt for baggage
• a baggage belt

Spanish often leaves out the article after de when talking about a thing’s type, purpose, or material:

• zapatos de cuero = leather shoes
• taza de café = coffee cup
• cinta de equipajes = baggage belt

If you said de los equipajes, it would sound like you mean specific, already identified luggage, not baggage in general.

Yes, equipaje is also possible, and many learners will meet equipaje more often as the basic dictionary form.

The difference is mostly about usage and style:

• equipaje is often treated as a mass or collective noun, like luggage
• equipajes can be used when thinking of many separate bags or the baggage belonging to many passengers

In airport language, plural forms such as recogida de equipajes are very common, so cinta de equipajes sounds perfectly understandable and natural.

That said, you may also hear:

• cinta de equipaje
• cinta de recogida de equipajes

All are possible, but the longer airport-style version is especially common in real-life signage and announcements.

No contraction is needed here.

In Spanish, only these two contractions are standard:

• a + el = al
• de + el = del

But with la, there is no contraction:

• a la stays a la
• de la stays de la

So:

• junto a la báscula is correct
• not junto al báscula

If the noun were masculine, then you would get a contraction:

• junto al mostrador

They show which syllable is stressed, and in some cases they also distinguish between different words.

está

• The accent shows the stress: es-TÁ
• It also distinguishes the verb está from esta, which can mean this in some contexts

báscula

• The accent shows the stress is on the first syllable: BÁS-cu-la
• Without the accent, Spanish stress rules would make it sound different

So the written accents are important both for pronunciation and for meaning.

In standard peninsular Spanish, roughly:

• cinta → /ˈθinta/
• equipajes → /ekiˈpaxes/
• báscula → /ˈbaskula/

A few helpful pronunciation notes for Spain:

• c before i in cinta is usually pronounced like the th in think in most of Spain
• g before e in equipajes sounds like a strong throaty sound, similar to the ch in Scottish loch
• báscula has the stress on the first syllable

If you hear Latin American pronunciation, cinta is usually /ˈsinta/ instead.

Yes. In Spain, báscula is a normal word for a weighing scale, especially a machine used to weigh something, such as luggage.

Depending on context, you might also hear:

• balanza for a scale or balance, often in more general or technical contexts
• peso in very informal speech when people are talking about the weighing point rather than the device itself

But in an airport setting, báscula is a very plausible and natural word.

It is understandable and natural, but airports often use longer set phrases.

Very common alternatives include:

• La cinta de recogida de equipajes está junto a la báscula.
• La cinta transportadora está junto a la báscula.

Nuance:

• cinta de equipajes focuses on the baggage belt itself
• cinta de recogida de equipajes sounds more specifically like the baggage-claim carousel
• cinta transportadora is more general, like conveyor belt

So the sentence you have is fine, but in real airport Spanish you may often hear one of those slightly fuller versions.