Is it appropriate to give a student personal advice?
Bachelor's students can know little about the outside world. Many may not have even done simple things like pay bills. Furthermore, in most countries they have either gone direct from high school to college, or direct to college after 1 year to travel or improve an entrance exam score.

You should lead with a disclaimer, and proceed to tell them at least 2 sides to their problem. Honestly, the advice you give will comprise of things they would not easily or never imagine themselves (in a short timeframe). It's either your advice or the aggregate advice from the internet. You will be one data point, but a credible one. Sometimes just advising (or encouraging) someone to actually bring their issue to the appropriate person is the push they need.

If you are constantly sought out for advice, I think it shows your opinion and life experiences are trusted. Considering the personal matters, I highly doubt the same students are asking more than 1 other professor. Be wise. Share your wisdom.