Burnt Sienna is one of the most classic earth tones, an earth orange that ranges from an orangey brown through to a peachy gold. It is often used to mix up a range of browns and to neutralize blues, which are its opposite.
Burnt Sienna is just one of many earth tones that are traditionally made with PBr7 (Pigment Brown #7); others include Raw Sienna, Raw Umber, and Burnt Umber. So basically all of them. PBr7 colors vary quite a bit in granulation depending on who you get them from. Holbein’s earth tones, like this one, tend to be quite creamy and smooth without granulation.