Ads are allowed; blocking the content is not. Google's 2012 page layout algorithm hit pages giving "a large fraction of the site's initial screen real estate to ads", but not ads above the fold "to a normal degree". Since January 10, 2017, mobile pages hidden behind intrusive interstitials "may not rank as highly"; cookie notices, age gates and "banners that use a reasonable amount of screen space" are exempt.
Affiliate sites are fine too: "Not every site that participates in an affiliate program is a thin affiliate." Thin affiliation, copied merchant text "without any original content or added value", is spam. Mark affiliate links rel="sponsored", never cloak them with sneaky redirects, and see Ad Networks on ad networks.