If you have just arrived to Athens by plane, probably this would be the first place of the Places to Go in Athens that you will see o the way to your place to stay in Athens. If you are using Public Transport in Athens, both metro or bus X95, they will bring you exactly to this central location in Athens - the Syntagma Square.
In Greek language it is written as σύνταγμα and the meaning has slightly changed since the ancient times. In Ancient Greece people used the ancient Greek language, which many linguists find very difficult. The word "Syntagma" meant "arrangement". Nevertheless in modern Greek, the simplified version of Greek language, it is translated as "Constitution"
The Syntagma Square is indeed at the top of most central places in Athens.