A hostile work environment exists when an employee experiences workplace harassment and fears going to work because of the offensive, intimidating, or oppressive atmosphere generated by the harasser based on race, religion, sex, national origin, age, disability, veteran status, or, in some jurisdictions, sexual orientation, political affiliation, citizenship status, marital status, or personal appearance.
A hostile work environment may also be defined as when a boss or manager begins to engage in a manner designed to make you quit in retaliation for your actions. Suppose you report safety violations at work, get injured at work, attempt to join a union, complain to upper level management about a problem at work, or act as a whistleblower in any respect. Then, the company's response is to do all manner of things to make you quit, like writing you up for work rules you didn't break, reducing your hours, scheduling you for hours that are in total conflict with what you can do, or reducing your salary. The company's reaction can be viewed as creating a hostile work environment, one that makes it impossible to work and is an attempt to make you quit so that the employer does not have to pay unemployment benefits.
You do have rights to sue for the manager's actions.