What is the ruling of Islamic law regarding my friend's continued employment as an accountant in a company where her manager and colleagues embezzle its funds, while she is subjected to pressure to keep silent, and what do you advise her to do?

The girl must change the evil that her manager and colleagues are committing by embezzling funds, to the best of her ability. If she is unable to do so, then with her heart. It is preferable for her to move to another job or another department within the company if possible. She should remind them of the ugliness of their actions and use booklets or tapes to give to them as guidance.