Homebridge is.. a bridge between something and Apple's HomeKit. Homebridge has plug-ins that integrate a something. There's an astonishing array of Homebridge plug-ins... and Hubitat has two that you should consider.
homebridge-hubitat-makerapi and homebridge-hubitat-hubconnect
They are made by @dan.t and are functionally equivalent. You can integrate using a built-in App called MakerAPI or via a Community created way to interconnect hubs, called HubConnect.
If you are connecting Hubs then you will want to use HubConnect. You can have both MakerAPI and HubConnect running, and many do. But once you've spent the time to get HubConnect working and 'mirroring' devices between hubs, why not stick with the same interface? 
Either way, you select the list of Hubitat devices you want HomeKit to know about, and your Apple devices will find a Homebridge Appliance to add and the devices will become available in the Home app. It's Apple's restriction to not allow other devices discovered via other Appliances to be sent back to Hubitat. You can work around this by creating 'virtual' devices like switches and dimmers, that can be sent to HomeKit and via Apple Automations get tied to the virtual device back to Hubitat.
HOOBS is the Homebridge product with a lovely User Interface pre-integrated. It makes it easy to alter the config of Homebridge and all of it's plugins.. of which maybe you only have one.. like me.
HubLink is an early mechanism for tying 2 hubs together. It has some limitations but for a basic interconnect, it still works. HubConnect was created to eliminate all of the limitations. Because it's not built-in, the installation process has a lot of steps but once you get it installed, it will amaze.
You begin by choosing one of your Hubitat hubs to be the Server, the hub that all other hubs will connect to, and add a pair of Apps and a Driver as code. A simple copy/paste, repeated. On each Remote hub, you add an App and a Driver, as code, simple copy/paste.
From there you tell Server to create a remote hub, define it and copy a Key from the server to the Remote. The two hubs will connect and the "highway" between is ready for you to allow cars and trucks (Zwave, Zigbee, LAN, etc. devices) to use the highway. 
There's videos and installation instructions for everything mentioned...
For Homebridge, use this tool:
https://dantapps.github.io/
To create a perfect config that will paste right into HOOBS.
For HubConnect, there's a pair of sites:
https://hubconnect.hubitatcommunity.com/
and
https://hubconnect.to/
You'll have more questions I'm sure, ask away... 