La camisa és tan barata com els mitjons a la botiga.

Tan ... com means as ... as.

So:

• tan barata com = as cheap as

This is the standard Catalan pattern for expressing equality in comparisons:

• tan + adjective/adverb + com
• tant/tanta/tants/tantes + noun + com

In your sentence:

• La camisa és tan barata com els mitjons
  = The shirt is as cheap as the socks

A useful contrast:

• més barata que = cheaper than
• tan barata com = as cheap as

So tan ... com is not saying one is cheaper; it says they are equal in cheapness.

Because barata has to agree with la camisa.

In Catalan, adjectives usually agree in gender and number with the noun they describe.

• camisa is feminine singular
• so the adjective is barata = feminine singular

Compare:

• el mitjó barat = the cheap sock
• la camisa barata = the cheap shirt
• els mitjons barats = the cheap socks
• les camises barates = the cheap shirts

In the sentence, barata describes la camisa, not els mitjons, so it stays feminine singular.

Catalan uses the definite article more often than English.

So els mitjons literally means the socks, but in many contexts English would simply say socks.

In Catalan, using the article with nouns is very normal, especially when talking about specific things already understood from context.

Here:

• la camisa = the shirt
• els mitjons = the socks

This does not sound overly definite in Catalan. It is just natural grammar.

Mitjons is plural.

• un mitjó = a sock
• els mitjons = the socks

Like English, Catalan normally talks about socks in the plural when referring to a pair or to socks generally.

Also note the gender:

• mitjó is masculine
• so the plural article is els

That is why you get:

• els mitjons

not:

• les mitjons

Because cheap is being treated as a quality or characteristic, not a temporary state or location.

• és comes from ser
• està comes from estar

In Catalan, ser is used for things like identity, description, and general characteristics:

• La camisa és barata = The shirt is cheap

That is the natural choice here.

You would not normally say La camisa està barata in standard usage for this kind of simple comparison.

A la botiga means at the shop/store or in the shop/store, depending on context.

• botiga = shop / store
• a la botiga = at/in the shop

In everyday Catalan, a is very commonly used with places:

• a casa = at home
• a l’escola = at school
• a la botiga = at the shop

So this part tells you the setting or location connected with the sentence.

This is a very good question, because the sentence can feel a little ambiguous.

La camisa és tan barata com els mitjons a la botiga.

Most likely, a learner will understand it as something like:

• The shirt is as cheap as the socks at the shop or
• At the shop, the shirt is as cheap as the socks

Because a la botiga comes at the end, it may sound like it is closest to els mitjons, but in real use it can also apply more broadly to the whole comparison.

If you want to make it clearer, Catalan speakers might rephrase:

• A la botiga, la camisa és tan barata com els mitjons.
  = At the shop, the shirt is as cheap as the socks.

or

• La camisa és tan barata com els mitjons de la botiga.
  = The shirt is as cheap as the shop’s socks / the socks from the shop.

So yes, the original sentence is grammatical, but the final phrase can leave a bit of room for interpretation.

Yes, but it would mean something different.

• tan barata com els mitjons = as cheap as the socks
• més barata que els mitjons = cheaper than the socks

So:

• tan ... com expresses equality
• més ... que expresses superiority

If the idea is that both cost about the same, use tan ... com.

Because la camisa refers to a specific shirt.

• la camisa = the shirt
• una camisa = a shirt

Using the definite article suggests that the speaker and listener can identify which shirt is meant, or that it is the shirt being discussed.

If you changed it to una camisa, the meaning would become less specific:

• Una camisa és tan barata com els mitjons a la botiga.

That could still be grammatical, but it would mean a shirt rather than the shirt, which changes the nuance.

A rough guide for English speakers is:

• mitjons ≈ mee-JONS or mee-JOHNS

The tj sound in Catalan is not exactly like English, but that approximation is often helpful at first.

A fuller rough pronunciation of the whole sentence is:

• la ka-MEE-zuh ez tan buh-RA-tuh kom elz mee-JONS uh luh buh-TEE-guh

A few notes:

• camisa has stress on -mi-
• barata has stress on -ra-
• botiga has stress on -ti-
• és is pronounced like a short stressed ez

This is only an approximation, but it can help you get started.

Yes. Catalan word order is fairly flexible, especially when you want to emphasize the place or topic.

The original sentence is fine:

• La camisa és tan barata com els mitjons a la botiga.

But you could also say:

• A la botiga, la camisa és tan barata com els mitjons.

This version makes the location clearer right away: At the shop, the shirt is as cheap as the socks.

So the original order is grammatical, but a different order may sound clearer depending on what you want to emphasize.