Original sentence: A saiga’s nose warms the air and traps sand dust.
Correct sentence: A saiga's nose warms the air and traps sand and dust.
Why: The apostrophe in "saiga's" is correct (it shows the nose belongs to the saiga). The verbs "warms" and "traps" are correct. "Sand dust" sounds odd; we say "sand and dust" to list both things.
One-sentence version for a 6-year-old: A saiga's nose warms the air and catches sand and dust.