Very good question.
HR can give advice on procedures and labor law when employees are in a certain situation like: they want to quit their job, they want a raise, they want to leave on maternity leave, they want to attend a certain training, they want to go on vacation or they are sick and need to stay home.
HR gets involved in employee conflicts and disciplinary actions as mediator.
HR explains unclear matters to employees like how was the salary calculated, what do I need to do to benefit of training costs for a certification subsidizing, what benefits do I have from the medical provider, how to apply for a promotion, etc.
HR prepares paperwork for bank loans that employees need for the bank file.
HR can offer useful feedback after a promotion session to rejected employees.
HR can recommend external trainings that are not organized by the company and that might interest the employees.
HR sends periodical newsletters to employees with useful information about the company, open positions, rules and regulations to follow.
and many more...