Employees, like other data subjects, have the right to access their personal data. When you receive a SAR (Subject Access Request) you need to reply without undue delay (usually one month) and you can extend such a period to another month for complex requests.
You need to give access to the employee to data stored excluded for documents subjects to legal privilege (i.e. legal advice on the employee), data concerning third parties, disproportionate request.
Please consider that if the SAR is too generic you can ask for clarification to the employee, if the employee is not legitimate to access, you can reply with a denial, but do not ignore the request otherwise the employee can lodge a complaint to the Data Protection Authority of your country.