Endpoint Protection

Need step by step about usb exclusion from sepm and blocking exclusion. Also is it possible to exclude application and device control policy orr it possible only from Hardware components.

See this:

Block or allow devices in Endpoint Protection

How to block USB flash drives while allowing other USB devices.

You can withdraw the policy for specific groups or set to log only mode

What is actual meant of Heartbeat. And what we can do after we know it.

The SEP client heartbeat interval is normally controlled by communications policies set at the Symantec Endpoint Protection Manager (SEPM). In certain situations, the SEP client will decrease its heartbeat interval to a value between 0 and 60 seconds. The purpose of this accelerated heartbeat is to ensure that critical updates and content are delivered to clients in as timely a manner as possible. Once the client is able to download the content update or package requested, the client will then re-apply the heartbeat interval configured at the SEPM level. It is not possible to configure clients' Accelerated Heartbeat intervals https://www-secure.symantec.com/connect/forums/sepm-servers-hearbeat

Please refer to your other thread for this answer.