The most common ways to help a distressed student are as follows. The first thing to be done is to speak to the student in private and to discuss what exactly is causing their distress. In such a way, you will at least be able to see the tip of the problem.
If you see that the student is reaching out for help, do your best to provide them with everything they need. Make sure that you are there for them as quite often the thing which they need the most is someone’s support. Apart from that, it will also be really useful for a student to talk to someone who has gone through the same thing. In such a way, they will be sure that everything can be dealt with no matter how scary it seems at first.
Do not forget that you should not judge or criticize the person and their experiences. They are struggling which means that they are already under a lot of stress. The last thing they need in such situations is someone telling them how to behave. Be as supportive as possible.