It changes URLs you manually enter, choose from bookmarks or search engines to redirect to affiliation networks.
Caught it when it changed my bookmarked banking login: https://banking.barclaycard.*** and NoScript complained.

Conceals this action in description:
"We also want to point out that by installing the extension, you allow developers to receive a cashback from your purchases on other online stores (except AliExpress) as a reward for using the extension."