ACL in Fortiswitch

Hello Khaled_atta, 

Thank you for using the Community Forum. I will seek to get you an answer or help. We will reply to this thread with an update as soon as possible. 

Thanks, 

 Fortinet Community Team 

Hello Khaled_atta,

Thank you for using the Community. 

The switch doesn't keep track of the traffic in both directions as it is not a stateful firewall, access list will need to be configured for both. 

I found an example which may be interesting for your question in the doc. In Configuration Examples > Example 1, only one ACL configured blocking a traffic to a specified destination and all other destinations are allowed. 

The default action is allow unless specifically configured. 
Please let me know if this helps :)