A fundamental station is like a very special place on the ground where people who study the Earth can go to take very accurate measurements of its shape and movement.
Just like how we all have our own unique fingerprints, the Earth has its own unique shape and movement too. It's important for scientists to know and understand these things so they can better predict things like earthquakes and tsunamis.
At a fundamental station, scientists use really fancy equipment to measure things like gravity, temperature, and the Earth's magnetic field. They also use lasers and GPS to determine the station's exact location and how it's moving in relation to the rest of the Earth.
All of these measurements are very precise and help scientists make more accurate models of the Earth, which can help us better understand and prepare for natural disasters. So, a fundamental station is kind of like a special laboratory where scientists go to learn more about the Earth and how it works.