"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.