What is Execute ACL property? In which scenario we have to use?
Execute ACL: ACL that governs which user groups on your server can use this web service endpoint alias. Select an ACL from the drop down list. By default, only members of groups governed by the Internal ACL can use this alias.
Integration Server performs the ACL check only if the specific endpoint alias is used as the value of the endpointAlias input parameter in a web service connector or the pub.client:soapClient service. Integration Server does not perform the ACL check when the consumer web service endpoint alias is assigned to a binder used by the web service connector
For more details please have a look into Integration Server Documentation: