What did God provide to shade Jonah's head outside Nineveh?

Answer: A plant

The LORD God appointed a plant (a vine or gourd) to grow up over Jonah's head for shade, and Jonah was greatly pleased with it.

“So the LORD God appointed a vine, and it grew up to provide shade over Jonah’s head to ease his discomfort, and Jonah was greatly pleased with the plant.”— Jonah 4:6 (BSB)