The spell that produces light from a wand is Lumos.
Lumos is a wand-lighting charm in the Harry Potter series. When cast, it creates a small illuminated glow at the tip of the wand, allowing a witch or wizard to see in darkness without using a torch or other Muggle device.
The charm is commonly paired with Nox, which extinguishes the light produced by Lumos. This makes the two spells easy to confuse with one another: Lumos turns the wand light on, while Nox turns it off. The names are based on Latin words connected with light and night.
Other options serve different purposes. Accio summons an object, Incendio produces fire, and Nox ends the wand-lighting effect. The related spell Lumos Maxima creates a stronger burst of light and appears in the wider wizarding world, but the standard answer to this question is simply Lumos.