IBM’s mobile offering has seen many name changes in recent past. IBM acquired Worklight in 2012 and initially kept the name. Big Blue then renamed it IBM Worklight Foundation in 2014 before recently doing away with the Worklight moniker altogether. It's now "IBM MobileFirst Platform Foundation."
Functionally, though, not much has changed. What you get is mainly a platform for building hybrid mobile apps based on Apache’s Cordova hybrid container. There’s support for other types of apps — notably mobile web and native apps, but conditions apply.
More recently, however, IBM has improved integration with their "Digital Experience" suite. What this really means is closer integration between IBM’s WCM and Mobile capabilities. So you can now create content in WCM and make it available, via services, to your mobile apps created using MobileFirst. In addition, there is a new interface/content authoring portlet for creating mobile content (an improvement, since current authoring portlets have major usability issues).
This is a useful capability and something I have discussed earlier, for example in this post.
So if you are already an IBM customer — meaning you have invested in IBM WebSphere Portal and WCM and have entitlements for MobileFirst — this is good news for you. But remember that while this combined solution can target a lot of scenarios, it remains a complex set of platforms. For most of you, it will constitute too many repositories, servers, and integration points, and you will need serious IBM talent to manage the setup. Also, for a lot of mobile scenarios, IBM WCM will probably be overkill. Fortunately, there are simpler WCM alternatives that you can consider.