Learn French: C'est un bijou précieux que j'admire beaucoup. - This is a precious piece of jewelry that I admire a lot.

In this sentence, que (that) is the direct object of the verb admire. You can figure this out by asking: "I admire what?" The answer is the jewelry. Whenever the relative pronoun acts as the object of the action in the new clause, we use que. If it were the subject actually doing the action, we would use qui.

Is précieux plural here because it ends in an -x?

No, it's singular! We know this because it is describing un bijou (a single piece of jewelry). The adjective précieux naturally ends in an -x in its masculine singular form. Conveniently, it stays exactly the same when describing plural masculine nouns (des bijoux précieux).

Why does the adjective précieux come after bijou?

In French, most adjectives are placed after the noun they describe. Only a small group of very common adjectives—usually describing Beauty, Age, Goodness, or Size (often remembered as BAGS)—go before the noun. Since précieux doesn't fit into that special group, it follows the normal rule and goes after the noun.

Why does the sentence start with C'est instead of Il est?