Yes, "Active" usually means available and I agree with William below: when using an internet service outside of a direct MLS link such as Realtor.com, Zillow and the like, you can't always assume the status to be accurate.
Nowadays, a listing is built in the Multiple Listing Service by hand by a listing agent, depending on the MLS agreement with their local board & area, it is very likely and common that the listing will then populate on multiple real estate related websites who have what is called an IDX (or internet data exchange) agreement with these sites. This is what we call in our industy, syndication. What this does for you, the buyer, is ensures that one way or another, you're going to stumble upon this house for sale on the internet somwhere.
What happens in syndication is that depending on the receiving website's platform (how it is built and functions internally) information from the MLS listing is grabbed and plugged into matching fields on the new website. So that's why sometimes you'll see the same home listed with 2 baths and other times you'll see it listed with 1 and a half. Most likely, the home actually has 1.5 baths, but the receiving platform did not have an option to "pull in" a half bath into their field, so it defaults as a 2 bath. How does that relate to your question? Doesn't really--just some added info to understand why even though these web sites are awesome to begin your search on, the best and most accurate way to get reliable information is working with a real estate agent.
But, to get back to your question, syndication also is not immediate, so when an agent changes a price in the MLS or changes that status from "active" to "pending" it can take up to 72 hrs for some syndicated sites to re-populate with the updated data! THAT's why you'll find that you can get your hopes up and fall in love with a property that says it's available then you call your agent only to find that it went into escrow 3 days ago.
If you are serious about buying a home, you need to be working daily with an agent. And the best sites for accurate data are usually links provided to you from your agent for direct updates from the MLS. It's the only way to avoid having your hopes dashed when you find the home of your dreams and then find out that apparantly it was someone else's too and they found out about it before you did and got their offer accepted before the sydnicated website you are using even pulled it in from the MLS.
Good Luck and happy house hunting!