Ese traje gris es elegante.

Both are demonstratives, but they point to different degrees of distance.

• este traje = this suit (closer to the speaker)
• ese traje = that suit (a bit farther away, or already mentioned)

So ese is the masculine singular form that goes with traje.

In Spanish, a demonstrative like ese already works as a determiner, so you normally do not add el before the noun.

• ese traje = that suit
• not ese el traje

It works like English: you say that suit, not that the suit.

Nouns in Spanish have grammatical gender, and traje is a masculine noun:

• el traje = the suit

Because it is masculine singular, the demonstrative must match it:

• ese traje
• not esa traje

This is grammatical gender, not biological gender.

In Spanish, most descriptive adjectives usually come after the noun.

• traje gris = gray suit

That is the normal word order. English usually puts color adjectives before the noun, but Spanish usually places them after it.

So:

• un coche rojo
• una camisa blanca
• un traje gris

Some Spanish adjectives change clearly for gender, but gris does not in the singular.

• traje gris
• camisa gris

So it can be masculine or feminine without changing in the singular.
In the plural, it usually becomes:

• trajes grises
• camisas grises

Because elegante is the adjective that describes the subject through the verb es.

The structure is:

• Ese traje gris = the subject
• es = the verb
• elegante = the description

This is very common in Spanish:

• La casa es grande
• El libro es interesante
• Ese traje gris es elegante

Spanish often distinguishes between ser and estar.

Here, es is used because elegante is describing a more general or inherent quality of the suit. It is being presented as an elegant suit by nature or style.

• es elegante = it is elegant

If you used está elegante, that would usually suggest something more temporary or situational, often about how someone or something looks at that moment.

For clothing, es elegante is the normal choice when talking about style or character.

Because elegante is one of many adjectives that has the same form for masculine and feminine in the singular.

• un traje elegante
• una falda elegante

In the plural, it changes to:

• trajes elegantes
• faldas elegantes

So it does agree, but not by changing masculine vs. feminine in the singular.

Yes. That is also correct, but it means something slightly different in structure.

• Ese traje gris es elegante = That gray suit is elegant
  • gris is part of the noun phrase and identifies which suit you mean.
• Ese traje es gris y elegante = That suit is gray and elegant
  • now both gris and elegante are linked to the verb and are being asserted about the suit

So both are possible, but the emphasis is different.

In this sentence, traje is definitely a noun meaning suit.

But yes, traje can also be a verb form:

• traje = I brought (from traer)

For example:

• Traje el libro ayer = I brought the book yesterday

In Ese traje gris es elegante, the word is clearly a noun because it comes after ese and is being described by gris.

No. In modern standard Spanish, ese is normally written without an accent mark.

So:

• ese traje

not

• ése traje

Older rules sometimes allowed accent marks on demonstratives in special cases, but current standard usage generally does not.

You would make the demonstrative, noun, verb, and adjectives agree as needed:

• Esos trajes grises son elegantes.

Changes:

• ese → esos
• traje → trajes
• gris → grises
• es → son
• elegante → elegantes

A common Spain pronunciation would be roughly:

• EH-seh TRA-heh GREES ess eh-leh-GAHN-teh

A few useful points:

• j in traje is the strong Spanish sound, like a throaty h
• g before e in elegante is also that same strong sound
• Spanish vowels are short and clear:
  • e as in eh
  • i as in ee, but shorter

The stress is:

• TRA-je
• e-le-GAN-te

You can, but it sounds more literary, expressive, or stylistically marked.

• ese traje gris elegante is also not the best normal version if you mean that gray suit is elegant
• the standard sentence is Ese traje gris es elegante

If you put elegante before the noun:

• ese elegante traje gris

it sounds more like that elegant gray suit, with a more descriptive or polished tone. In everyday neutral Spanish, adjective placement before the noun is much more limited than in English.