"Per se" is a
Latin term that means "in itself" or "by itself." When combined with "pay," the phrase "pay per se" is often used to emphasize that payment is the primary or sole consideration, rather than any other factors that
may be involved.
For example, if you say "I'm not interested in the perks that
come with the job, I just want to be paid fairly, pay per se is what matters most to me," you are emphasizing that your primary concern is the salary or wages you will receive, rather than any other benefits that
may be offered.
In other
words, "pay per se" means payment itself, without any additional factors or considerations.