It was gifted to Kronos from AMD where it had been called mantle.

after you google it first, please.

For example, capturing a game screenshot. In OpenGL you have a method glReadPixels which will flush the GPU queue, wait for operations to finish, read the screen pixels, convert them and put them into an array. All in one method, all outside of programmer's control, done somewhere in the driver. Meanwhile in Vulkan, same task requires programmer to flush GPU, wait for operations to finish, allocate memory for an image, create an image in linear format, transition image to proper state (transfer destination), transition swapchain image to transfer source, blit the pixels from swapchain image (which could be linear, could be tiled) to linear image, transition swapchain image back, map memory of the linear image. A single line of code in OpenGL translates to about 50 lines of Vulkan code (lot of it is stuff you'll write once and reuse everywhere else), but you have full control over each of the steps.