https://dieselnet.com/standards/us/ld_ca.php#levii
This link lays out the cryptic details and ratings if you're interested
In summary, this truck/year has to qualify under the "Lev III" standards. Which looks California specific (some other states follow the same standards). According to the table, 14,000 lbs. and under needs to show they pass emissions standards.
The emissions badge on this sticker shows ULEV270, which is under the Lev III standard.