Namasté is a word that comes from a language called Sanskrit, which is very old and is used in India. It is a way of greeting people or saying goodbye in a respectful way.
When someone says namasté, they bring their hands together in front of their chest and bow their head a little bit. This is called a "prayer position". It is a way of showing the other person that they are important and that you are being polite to them.
The word namasté itself means something like "I honor the place within you where the whole universe resides." This means that when we say namasté, we are saying that we respect and honor the other person, and that we recognize that they are important and connected to everything in the world.
So when someone says namasté to you, it's like they're saying, "Hello, I think you're special and I'm glad to be with you." It's a really nice way to greet someone!