Celle-ci est moins chère, mais je préfère celle-là.

They are demonstrative pronouns. They mean this one and that one, and they replace a noun instead of repeating it.

In this sentence, the noun is understood from context. For example, if you were comparing two robes or two tables, French can avoid repeating the noun and just say celle-ci / celle-là.

• celle-ci = feminine singular = this one
• celle-là = feminine singular = that one

There are matching forms for other genders and numbers too:

• celui-ci / celui-là = masculine singular
• celle-ci / celle-là = feminine singular
• ceux-ci / ceux-là = masculine plural
• celles-ci / celles-là = feminine plural

Because celle is used when you want to say the one and replace a feminine singular noun.

Compare these:

• cette robe = this dress
• celle-ci = this one (where dress is understood)

So:

• ce / cette / ces are usually demonstrative adjectives and go before a noun
• celui / celle / ceux / celles are demonstrative pronouns and replace the noun

ça means something more like that or it, but it does not work the same way as the one.

They help distinguish between two things.

• -ci usually means this, something closer
• -là usually means that, something farther away

So:

• celle-ci = this one
• celle-là = that one

In real modern French, especially in conversation, the distance idea is often less strict. Sometimes -ci and -là are mainly used just to contrast two items clearly.

Because in French, -ci and -là are attached with a hyphen to demonstrative forms.

So you write:

• celle-ci
• celle-là

not:

• celle ci
• celle là

The hyphen is standard spelling.

Because the adjective must agree with the noun being referred to, even if that noun is not repeated.

If the hidden noun is feminine singular, the adjective must also be feminine singular:

• masculine singular: cher
• feminine singular: chère

So if the implied noun is something like une robe, une voiture, or une chaise, you use chère.

The accent in chère is part of the normal feminine spelling of cher.

Moins means less, and it goes before the adjective:

• moins chère = less expensive

This is the standard French pattern for a comparative with an adjective:

• moins + adjective = less + adjective
• plus + adjective = more + adjective
• aussi + adjective = as + adjective

Examples:

• moins chère = less expensive
• plus chère = more expensive
• aussi chère = as expensive

If you want to say less expensive than, you add que:

• Cette robe est moins chère que l’autre.

Because moins does not stop adjective agreement.

Even in a comparative, the adjective still has to match the noun in gender and number.

So if the implied noun is feminine singular, you get:

• moins chère

If it were masculine singular, you would say:

• moins cher

For example:

• Ce téléphone est moins cher.
• Cette montre est moins chère.

Because celle-ci is the subject of the sentence, and est is the verb être in the il/elle/on form.

Even though celle-ci means this one, grammatically it behaves like a third-person singular subject:

• Celle-ci est... = This one is...

So the structure is completely normal:

• subject = celle-ci
• verb = est
• adjective phrase = moins chère

Because préférer takes a direct object in French.

So you say:

• Je préfère celle-là.

not:

• Je préfère à celle-là.

This is similar to English I prefer that one, where that one is the direct object.

You can also compare two things explicitly:

• Je préfère celle-là à celle-ci.

That means I prefer that one to this one.

The accent grave in là is part of the standard spelling.

It helps distinguish là from la, which can be:

• the feminine article: la
• an object pronoun: la

In celle-là, the là is the demonstrative element meaning that.

So the accent matters in writing.

It is completely natural and normal, both in writing and in speech.

French speakers do use forms like:

• celui-ci / celui-là
• celle-ci / celle-là

However, in casual everyday speech, people may sometimes prefer simpler wording depending on context, especially if pointing at objects. Still, this sentence sounds perfectly standard and idiomatic.

A simple pronunciation guide is:

• celle-ci ≈ sel-see
• est ≈ eh
• moins ≈ mwain
• chère ≈ sher
• mais ≈ meh
• je préfère ≈ zhuh pray-fehr
• celle-là ≈ sel-lah

A more careful IPA version is:

• Celle-ci est moins chère, mais je préfère celle-là.
• /sɛl.si ɛ mwɛ̃ ʃɛʁ mɛ ʒə pʁefɛʁ sɛl.la/

In natural speech, je is often very light, and moins has a nasal vowel, which may take practice for English speakers.