is this hole in balcony useful?

Question

Before I fill this hole with foam, is it actually here on purpose? There are three of them on my balcony at different points where the wall meets the floor, and I can't think of a reason they would be useful.

There is also a large drainage hole in the corner that I'm fairly certain is for water runoff from balconies above. It's a new building (2020), 16 floors.

Answer 1

As others have said, it looks like a weep hole, to let any water that gets past the caulking drain out before it can become a bigger problem.

Bottoms of windows are often either left uncaulked, or have drain holes drilled into them, or both. Think of that door as a very large sliding window.