You can control the Pinterest Settings by clicking on the dedicated link in the plugin right side menu.
When this option is ON, the plugin will send Enhanced Matching data for your logged-in visitors.
What is Advanced Matching: it’s a Pinterest feature allowing you to securely send them info about your visitors. This info will help Pinterest to identify (match) the visitor and make a connection with an actual Pinterest account. This is useful for those instances when Pinterest can’t do it by the usual means, like existing cookies or logged-in account.
Pinterest Enhanced Matching only uses the email address.
You can find more about this option directly on the Pinterest help page