Nothing.
HR is almost certainly against you. By taking your problem to HR you are making it their problem. They do not want more problems (does anyone?) so they will try to deflect, redirect or otherwise avoid accepting ownership of your problem.
In theory HR wants to facilitate the firms access to the best available human capital to ensure the firm can compete effectively in the market. In the case of government/NFPs, the HR function is the same, but rather than creating profit the theory would hold that they seek to maximise social good through recruiting and retaining great people.
In practice, HR suffers from the agency problem. Let's assume you are a fantastic talent and someone the firm needs to retain to maximise its performance. HR would in theory want to work proactively to address this conflict and ensure you are retained and productive.
However, doing all that is a lot of hard work. Your HR person/people will likely get paid the same either way, so why bother? The principal's interests (retaining great talent) are in conflict with the agent's interests (not working hard).
In a poorly managed HR department, the team will view itself as a compliance function as other answers have suggested. This is normally with an exception for any pet projects any individual HR person wants to implement (think ridiculous 'culture building' activities).
Don't expect a compliance person to solve your problem. HR are there to police, so they'll write you a ticket if your tail light is out, but they are not going to help you fix it (unless fixing tail lights is on trend, then they'll gladly waste hours and ignore all crime to fiddle around in the general area of the tail light and somehow do more damage).
In a well managed HR department...scientists are still searching for one.
Bottom line: HR does nothing for you. But don't take it personally, they do nothing for anyone except themselves.