From the Wiki Page, The Seven Deadly Sins「七つの大罪 Nanatsu no Taizai」 were the strongest and cruelest order of Holy Knights in the kingdom of Liones, which was formed by seven brutal criminals, who had all been convicted for grievous crimes and had carved the symbols of seven beasts onto their bodies. After having been framed for murdering the Great Holy Knight, they were indefinitely disbanded, branded as traitors and villains. They are the main protagonists of the series.
That's all just gibberish to me. I collected the series of these Sinners premiums because the little doodad came with a lemon drink I like, すきっとレモン.
There are eight different ones: １：メリオダス (Meliodas, Sin of Wrath) ２：エリザベス (Elizabeth Liones, the one who enlists the aid of the Sins) ３：ディアンヌ(Diane, Sin of Envy) ４：バン(Ban, Sin of Greed) ５：キング(King, Sin of Sloth) ６：ゴウセル (Gowther, Sin of Lust) ７：ギルサンダー (Gilthunder, a Holy Knight) ８：ホーク (Hawk, a talking pig).
Not listed are the Sins of Gluttony (Merlin) and Pride (Escanor). I'm not sure why they weren't included with these doodads.
For descriptions of those characters in English check the link above or this one about the manga.
Here's a little video of the anime ads. No, it doesn't make much sense to me either, yet the pig is cute.
If anyone is a fan of this series, I'll be happy to send you some of these, I have a few extras.