The phenomenon you are referring to, where the sun passes directly overhead at noon, occurs at specific latitudes known as the Tropic of Cancer and the Tropic of Capricorn. On the first day of spring, the sun passes directly overhead at noon along the equator, an imaginary line at 0 degrees latitude. This event is known as the vernal equinox. During the vernal equinox, which usually falls around March 20 or 21, the tilt of the Earth's axis is such that the sun is positioned directly above the equator, resulting in equal amounts of daylight and darkness across the globe.
Therefore, on the first day of spring, you can observe the sun passing directly overhead at noon in locations situated along the equator, such as countries in the tropical region like Ecuador, Kenya, Brazil, Indonesia, and the Maldives.