First, welcome!
i agree with Dimples... sunburn. Vandas are high-light, high- heat plants, but sudden blast of direct sun can still toast leaves. Other than looking a bit ugly, no significant harm to the plant. Don't cut the damaged area because the surrounding green leaf can still photosynthesize. But you may want to place it where it gets a little shelter (a tree, a structure, etc) from the most intense mid-day sun.