Ad load describes the density of advertising in the experience: frequency of interstitials, how often rewarded offers appear, whether banners are persistent. It is usually managed with frequency caps and placement rules.
Higher load raises short-term ad revenue and can reduce retention, session depth and IAP conversion. The right level depends on the business model — an ad-funded casual game tolerates more than an IAP-led title where ads can erode the value of the paid experience.
Set a protected metric and an acceptable deterioration before testing a load increase, so the trade-off is decided before the results arrive.