The first public beta for OS X El Capitan 10.11.5 is now available. Those enrolled in Apple's Beta Software Program can grab it now from the Updates section of the Mac App Store.
This comes on the heels of the release of the first 10.11.5 developer beta. It's not known at this time what changes will come with OS X 10.11.5 when it launches publicly. It will likely feature a number of bug fixes and performance improvements.