If someone is "down-to-earth" it means they are very sensible. They have a very realistic view on things and have understandable expectations. It may be easier to understand what it means by taking an example of someone who is -not- down to earth. For example, someone who plays the lottery every week expecting to win each time may -not- be considered down to earth. It can be somewhat hard to describe as it comes from a standard sense of what is "normal" and as that's not the same for every person what you may consider down to earth may be slightly different from what someone else does. Basically though, I would consider it the opposite of an eccentric person.

What Mytch said. Another way to describe it would be to say that someone who is down to earth keeps things simple and doesn't over-complicate.

someone is "down-to-earth" it means they have just basic instincts ..... they are not spiritual people Usually they don't read and they don't understand classic literature.....