Learn French: Tu me le prêtes, je suis soigneux et je ne l'abîme pas. - You are lending it to me, I am careful and I am not damaging it.

In French, when you have two object pronouns right before a verb, 1st and 2nd person pronouns like me, te, nous, and vous always come before 3rd person pronouns like le, la, and les. Since me means 'to me' and le means 'it', the rule forces them into the me le order.

Why does the sentence use soigneux? Can it be soigneuse?

Yes, if the speaker is female. Soigneux is the masculine singular form of the adjective for 'careful'. Because the subject is je (I), the adjective must match the gender of the person speaking. A female speaker would say je suis soigneuse.

In the phrase je ne l'abîme pas, why does ne come before the pronoun l'?

In negative sentences, the ne is placed before the object pronoun, not just the verb. The object pronoun is tightly glued to the verb, so the negative words must surround the entire pronoun-verb package: ne + pronoun + verb + pas.

The sentence uses le in the first half but l' in the second half. Are they the same word?