Slots are specific to to the Tenancy product. These are the number of Ads in the rotation of a tenancy product ad feed.
The Tenants will split the share of voice between them. More than one slot ensures a single tenancy campaign does not 'oversaturate' a website. If the maximum 8 Slots is selected, each Advertiser who buys a slot for that time period will receive 1/8th of the traffic (impressions).