Imagine that the board is a terrain to be conquered. Whoever has the largest territory surrounded by their pieces wins at the end. For this, it is enough to surround the territory in the best possible way, not letting the opponent invade your land and take your territory.
The game ends when all disputes and territorial claims are over.
“If there’s intelligent life outside Earth, they’re sure to play Go.”
Emanuel Lasker. World Chess Champion (1894 and 1921)