A place or position that gives a good view of something.
Vantage is a good thing because it lets you see better.
Examples:
From this vantage, I can see the whole city.
The mountain peak is a good vantage for seeing the valley.
She stood on the vantage and looked out over the land.
The treehouse is a great vantage for spying on the neighbors.
The tall tower is the best vantage in the whole kingdom.
From this vantage, I can see everything, even the birds in the sky.