New hire is struggling, and I’m not sure the best way to help.

My team just hired a new entry level analyst and I got promoted to the senior role. This is her first job out of college and I think there’s a few things she’s doing unintentionally that are hurting how people view her. The number one is that she leaves early every day. We work a typical 8-5 schedule with an hour lunch and even on her first week the latest she stayed was 3:45. Now we don’t care how many hours you work as long as the work gets done and done well, but shes not exactly hitting it out of the park in that category either. Lots of her submissions have many mistakes that could easily be fixed with just more time spent validating. For context when I was in her role I never once left before 5pm until I had been there for a year. There’s always more work to take care of if you just ask. I feel bad for her because I think she’s just adjusting to the corporate world still and doesn’t really know how to operate yet. I want to help her, but as just a Sr analyst I’m not sure how I can approach it without me sounding like I’m overstepping or scaring her. Any suggestions on how I should approach this or if I should at all?