Solon is significant in the history of Western Civilization because he did a great deal to create the democratic system that was used in Athens during the high point of its civilization. We do not know exactly what he did because his actions have had all sorts of myths built up around them, but we do know that he averted a civil war in Athens and started them on the way to democracy.
Solon did this by publishing a series of laws that covered all aspects of life. Perhaps most importantly, he created a system in which more people could participate in government, with their ability to participate determined largely by their wealth. This led to the classical Athenian democracy.
Because of this, Solon's name has come to be used to refer to a wise lawmaker.