Consider yourself lucky - ETL-HR is one of the only ETL jobs that actually leads to experience that can be used outside of retail. Once you get tired of Target, you can go work HR at pretty much any other company in any industry with the experience you will get as an ETL-HR.
ETL-HR up until a few years ago used to strictly work 8-5 Mon-Fri and some weekends. They never had LOD shifts (basically what other companies call manager on duty). That changed a few years ago. Now they have to have LOD shifts, which means they will work all hours the store is open. So you might have a 2PM-10PM shift or a 7AM to 5PM shift. Could be all over the place. You will work every other weekend no matter what.
Your primary job will be hiring, firing, in charge of making sure reviews are done, dealing with TM complaining (some valid complaints, but expect lots of pointless whining and drama), answering benefits questions, going to college hiring events, usually in charge of stupid events that try to boost morale and never do, new hire orientation, and other things along those lines. Like I said - you will have to be LOD. That means you will have to get involved in other parts of the store at times - sales floor, logistics, guest service, etc. It is definitely not an office job. Too bad you weren't hired a few years ago.... back then ETL-HRs virtually never left their office for any reason.