Poblanos (pronounced po-blah-no) peppers are a mild variety of chile pepper. Some are as large a bell pepper but are skinnier and have a pointy tip, similar to hot chile peppers like jalapeños. Poblanos are best when peeled and seeded, which can be done more easily after cooking. They are commonly used in dishes like chile relleno, chiles en nogada, and rajas con crema.
As far as their level of spiciness, Poblanos clock in below the Jalepeno at 1500-4000 Scoville units.