Less is more in architecture means that keeping a design simple is often better than making it complicated with too many unnecessary details or decorations. Sometimes, having more things in a building can make it look busy and confusing.
Imagine you are building a house with blocks. You start with just a few, and it looks nice and neat. But then you add more and more blocks, and soon it looks messy and hard to understand.
In the same way, when architects design a building, they need to think carefully about what is really important and keep only what they need. This makes the building look more beautiful and easier to use.
This doesn't mean that the building has to be plain or boring. Architects can still use interesting shapes, colors, and materials. But they need to make sure that these elements don't overwhelm the building and make it harder to use or understand.
In the end, less is more in architecture because it helps the building do its job better and look more attractive.