Welcome to the forum.

She's a beauty! Looks like a 3 speed.

Centurion is an american marketing company that distributed bikes made overseas in the 80s - I believe they became Diamondback.

They are generally well thought of. I believe yours is an earlier model (judging from the headbadge) - others will weigh in on the specifics of the model.

Can you post pictures of the other side of the bike, showing the crank and rear gearing - sometimes that helps date the bike and model.