There are many businesses that could not define a PIP because they have no idea how to define performance. You can find one of these and hide for the rest of your career. If your PIP has milestones like 'write 10 emails per day' or 'participate in 10 hours of meetings per week', maybe you already found one of those companies. If you yourself struggle to define what 'performance' means in your job, isn't that a red flag all by itself? You can use this as an opportunity to understand the expectations of your employer (or at least your employer's agents). Or you can take this as a final confirmation that you are not achieving any personal fulfillment in this job. If you have to ask strangers, I sense you are quite lost in your current job.