Cloaking is where you attempt to show different content to Google's crawler compared to what visitors see and is a clear breach of their guidelines. If you hired a SEO company and you are not sure what they were up to then in Google Webmaster Tools (under Crawl -> Fetch as Google you can see what the Google crawler sees versus what you see when you visit any specific page on your site.
Redirecting is where you show visitors a link but when they click on it, the page it takes them to just redirects to another which Google often feels is "sneaky".
Note cloaking and redirecting may also be the result of a website that is hacked. See Hacked website penalty recovery for more on this.
Alternatively many webmasters become victim to this penalty because they hire SEO companies that carry out this practice.
If you are sure that neither you or anyone else responsible for the maintenance of your website has been involved in creating cloaked content or redirects it is possible that your website has been hacked and the content inserted. See hacked website penalty recovery for more information on this.
I'm Tim Hill, a Search Engine Optimisation and Online Marketing specialist. I created this site to help others understand that SEO is not a mysterious black art!.
If your a newbie try the Getting Started in SEO page, otherwise feel free to dig around and learn more.