Just be kind and empathetic to their situation

Depends

Ask them this very question. No human will answer it the exact same. Their needs will be specific.

Divorce is a horrible experience. All you can do is offer emotional support and advice (if they ask for it).

You can try to solve their problems by sawing the situation and seeing why they cannot solve it properly by conversation. But first, if they are not prepared or willing to change themselves, to pass through ego without the other passing too, they might not solve anything.

Divorce does not come because of not knowing how bad it is, it commonly is because the couple could not see any other way to choose.

man or woman?

you said you are close, how are you feeling about it all? about her and her child?

I'm sending you a hug!

maybe the best you can do to prepare for helping her is to be aware of what you're feeling and embracing it all, so you can also offer her this love space.