Leño literally means "log" or "piece of wood." However, in many Spanish-speaking contexts, especially in urban or informal settings, it's a common slang term for a "joint" (marijuana cigarette).
In this song, the line "Me prendes de cherry, un leño" clearly uses leño in its slang context, referring to lighting a joint. This dual meaning makes it an interesting and culturally relevant word to learn.
"UN LEÑO" is a smooth, flirty corrido-trap love song from Armenta with Chino Pacas, and it's basically one long list of promises to a girl. He'll take her to Paris and "te bajo las estrellas" (I'll bring the stars down for you), even buy her a castle "si así tú quisieras" (if that's what you wanted). He also says he put her name on something "pa' que veas que no ando con mamadas" (so you see I'm not messing around), which is very Mexican slang for being serious.
The title is the cheeky part. A leño is literally a log, but in Mexican slang it's a joint, so the hook "Me prendes de cherry, un leño" (you light me a cherry one, a joint) and "me encanta verte hacerlo" (I love watching you do it) are about smoking together. Listen for the casual Mexican words too: mija (short for mi hija, "my girl"), morenita (dark-skinned sweetheart) and compa (buddy), as in the shout-out "¿Sí o no, compa Chino?" (right, buddy Chino?). And pa' is just para with the end chopped off, which you'll hear in nearly every line.