Hi @Rut7 ,
If you select the condition "exists such as" , then the recipients in that Targeting Schema will be selected in the query.
Example:
If your Targeting dimension is "Recipients (nms:recipient), and if you apply filtering condition using "exists such as" operator by selecting the schema as "Recipient Delivery Logs (nms:broadLogRcp)" , then the recipients in "Recipient Delivery Logs (nms:broadLogRcp)" will get Targeted ie, the recipient should be present in the Delivery Logs Schema and also in the nms:recipient Schema

Please refer to the below documentation link for this operator, and alternative solution instead of using this operator and efficient way to use it.
https://experienceleague.adobe.com/docs/campaign-classic/using/automating-with-workflows/targeting-a...

Regards,
Pravallika.