Spanish has two verbs for to be: ser and estar.
Here we use ser because firme and cómodo describe qualities or characteristics of the stool. They are presented as inherent or defining features.
If you used estar, it would sound unusual here, because estar is more often used for states, conditions, or location, not general product qualities.
In Spanish, adjectives often come after the noun, especially when they describe ordinary qualities.
So:
This is normal Spanish word order.
In English, adjectives usually go before the noun: a firm, comfortable stool.
But in Spanish, after ser, adjectives naturally come after the verb:
Because este already works as a demonstrative determiner: this.
In Spanish, you normally do not say:
You say:
Just like in English you say this stool, not this the stool.
The written accent in cómodo shows where the stress falls: CÓ-mo-do.
Without the accent, Spanish spelling rules would suggest a different stress pattern.
The accent mark helps show the correct pronunciation.
Also, this accent mark is part of the normal spelling of the word, so it should always be written:
Yes. That is grammatically correct.
The order of adjectives linked by y can often be changed without changing the basic meaning:
Sometimes the order just reflects what the speaker wants to emphasize first.
For example, a seller might say firme y cómodo to stress stability first.
Y means and.
So:
Usually, yes, y is the normal word for and in Spanish.
One small exception: before words beginning with an i sound, Spanish often uses e instead of y for smoother pronunciation.
Example:
But in your sentence, y is correct.
A simple pronunciation guide is:
EH-steh tah-boo-REH-teh ess FEER-meh ee KOH-moh-doh
A few useful notes for Spain Spanish:
If you want a more Spain-specific pronunciation, z and soft c can sound like th, but this sentence does not contain that sound.