In the US, a progressive is someone who wants to see more economic and social equality - and hopes to see more gains in feminism and gay rights. They're also supportive of social programmers directed by the state - and they'd like social movements have more power in the US.
A more formal explanation might be; one favoring or advocating progress, change, improvement, or reform, as opposed to wishing to maintain things as they are, especially in political matters:
