D'Evils (a reference to the Jamaican Patois pronunciation of “the evils) is an ode to marijuana smoking. By smoking one spliff a day, he is keeping the "the evils” and stresses of everyday life away from him. He is able to relax and lower his worries.
It could also be a reference to Jay-Z’s classic song, “D'Evils.”
The song’s talk about smoking meshes well with the overall spacey vibe presented in the album.