Esta novela tiene noventa páginas y me parece fácil.

Because novela is a feminine singular noun in Spanish, so the demonstrative has to match it.

• este = this, for masculine singular
• esta = this, for feminine singular

So:

• este libro = this book
• esta novela = this novel

In Spanish, it is very natural to express length or quantity with tener:

• La novela tiene noventa páginas = The novel has ninety pages

Spanish often uses tener where English also uses have, so this part is quite direct.

You could think of it as the book contains ninety pages.

After numbers, Spanish normally puts the noun directly after the number:

• noventa páginas = ninety pages
• tres libros = three books
• veinte euros = twenty euros

You do not use de here.

Because the number is more than one.

• una página = one page
• noventa páginas = ninety pages

In Spanish, nouns usually become plural by adding -s if they end in a vowel:

• página → páginas

Because in Spanish, the subject is already understood from the context: esta novela.

So:

• Esta novela tiene noventa páginas y me parece fácil.

literally works like:

• This novel has ninety pages and seems easy to me.

Spanish often leaves out subject pronouns or repeated subjects when they are clear.

If you wanted to make it more explicit, you could say:

• Esta novela tiene noventa páginas y esta novela me parece fácil.

But that sounds repetitive, so native speakers normally omit the repeated noun.

Me parece literally means it seems to me.

So:

• me = to me
• parece = seems

Together:

• me parece fácil = it seems easy to me

In more natural English, that often becomes:

• I find it easy
• It seems easy to me

Because parecer is used to give an opinion or impression.

• me parece fácil = it seems easy to me / I think it’s easy

This is different from simply describing something with ser or estar.

• es fácil = it is easy
• me parece fácil = it seems easy to me / I find it easy

Using me parece makes the sentence sound more personal and subjective.

As for está fácil, that can exist in some contexts or varieties, but in standard Spain-focused learner Spanish, es fácil or me parece fácil is the more expected choice here.

Because the subject is singular: esta novela.

• La novela parece fácil = The novel seems easy
• Las novelas parecen fáciles = The novels seem easy

So parece matches the singular subject.

Some Spanish adjectives have the same form for masculine and feminine.

Fácil is one of them:

• un libro fácil
• una novela fácil

So even though novela is feminine, fácil stays fácil.

It only changes for number, not gender:

• una novela fácil
• dos novelas fáciles

Because when you are simply stating how many things there are, Spanish normally does not use an article:

• tiene noventa páginas = it has ninety pages

Using an article here would sound unnatural in this basic structure.

Yes, you could, but it means something slightly different in tone.

• Esta novela es fácil = This novel is easy
• Esta novela me parece fácil = This novel seems easy to me / I find this novel easy

The first is a straightforward statement. The second emphasizes your personal impression.

Because after verbs like ser, estar, and parecer, Spanish commonly uses an adjective to describe the subject:

• es interesante
• está cansado
• parece fácil

So fácil is functioning as the description of esta novela.

Y means and.

It joins the two parts of the sentence:

• Esta novela tiene noventa páginas
• me parece fácil

So the whole sentence means:

• This novel has ninety pages and seems easy to me.

You would change the words that need to agree with the noun:

• Este libro tiene noventa páginas y me parece fácil.

Notice:

• esta → este because libro is masculine
• novela → libro
• fácil stays the same, because it does not change for gender

Páginas is pronounced roughly like PAH-hee-nas in standard Spain Spanish.

The written accent mark shows where the stress goes:

• pá-gi-nas → stress on the first syllable

Without the accent mark, the stress rules would suggest a different pronunciation, so the accent is necessary.

Yes, it sounds natural.

It is clear, correct, and idiomatic for Spain Spanish:

• Esta novela tiene noventa páginas y me parece fácil.

A speaker might also say:

• Esta novela tiene noventa páginas y es fácil.
• Esta novela tiene noventa páginas y me resulta fácil.

But your original sentence is perfectly good and natural.