“Negative keywords for ad group” is an option that lets you set the common negative keywords for all keywords in a selected ad group.
The negative keywords for an ad group can be set on the campaign preview page:
You can also add them when creating or editing an ad group:
All negative keyword types are taken into account on Yandex.Direct. For example, if negative keywords for a single phrase, common negative keywords for a group of ads, or common negative keywords for a campaign are provided, then all them will be applied to the phrase, and there will be no impressions for all negative keywords.
The additional operators "!" and "+" are recognized in common negative keywords.
You will receive a warning in the client interface if the negative keyword is the same as any of your keywords. Impressions for the keyword will not stop, even if you leave the negative keyword in the list. It is also true for those cases, when the common negative keyword is fixed by the "!" operator. If it is necessary to exclude a particular form, it should be done at the phrase level.