We choose "Chat and Instant Messaging" category in "URL Category":

To block certain URLs we need to choose URL Reputation from 6 to 10.

Explanation Explanation Security Intelligence Sources ... Custom Block lists or feeds (or objects or groups) Block specific IP addresses, URLs, or domain names using a manually-created list or feed (for IP addresses, you can also use network objects or groups.) For example, if you become aware of malicious sites or addresses that are not yet blocked by a feed, add these sites to a custom Security Intelligence list and add this custom list to the Block list in the Security Intelligence tab of your access control policy. Reference: https://www.cisco.com/c/en/us/td/docs/security/firepower/623/configuration/guide/fpmc-configguide-v623/security_intelligence_blacklisting.html Explanation Security Intelligence Sources
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Custom Block lists or feeds (or objects or groups)
Block specific IP addresses, URLs, or domain names using a manually-created list or feed (for IP addresses, you can also use network objects or groups.) For example, if you become aware of malicious sites or addresses that are not yet blocked by a feed, add these sites to a custom Security Intelligence list and add this custom list to the Block list in the Security Intelligence tab of your access control policy.
Explanation Explanation Security Intelligence Sources ... Custom Block lists or feeds (or objects or groups) Block specific IP addresses, URLs, or domain names using a manually-created list or feed (for IP addresses, you can also use network objects or groups.) For example, if you become aware of malicious sites or addresses that are not yet blocked by a feed, add these sites to a custom Security Intelligence list and add this custom list to the Block list in the Security Intelligence tab of your access control policy. Reference: https://www.cisco.com/c/en/us/td/docs/security/firepower/623/configuration/guide/fpmc-configguide-v623/security_intelligence_blacklisting.html

Explanation
Cisco Hybrid Email Security is a unique service offering that facilitates the deployment of your email security infrastructure both on premises and in the cloud. You can change the number of on-premises versus cloud users at any time throughout the term of your contract, assuming the total number of users does not change.
This allows for deployment flexibility as your organization's needs change.

Explanation
Malware means "malicious software", is any software intentionally designed to cause damage to a computer, server, client, or computer network. The most popular types of malware includes viruses, ransomware and spyware. Virus Possibly the most common type of malware, viruses attach their malicious code to clean code and wait to be run.
Ransomware is malicious software that infects your computer and displays messages demanding a fee to be paid in order for your system to work again.
Spyware is spying software that can secretly record everything you enter, upload, download, and store on your computers or mobile devices. Spyware always tries to keep itself hidden.
An exploit is a code that takes advantage of a software vulnerability or security flaw.
Exploits and malware are two risks for endpoints that are not up to date. ARP spoofing and eavesdropping are attacks against the network while denial-of-service attack is based on the flooding of IP packets.