Meaning: from Greek miltos meaning "red earth".
Miltos is a short form of the name.
It's pronounced mil-ty-a-dis, mil-ty-a-dees or mil-tee-a-dis.
Miltiades is the name of several men in history, including an Athenian general responsible for the defeat of the Persians in the Battle of Marathon. Interestingly, the first time I came across this name was on an animated show called RWBY, in which the character is a female nicknamed Militia. The interesting thing about the show is that names of the characters (first and last) are based on colors.