What does this latest update entail/ consist of?

iOS updates described.

Most recent iPhone iOS update is 13.6.1:

OS 13.6.1

iOS 13.6.1 includes bug fixes for your iPhone.

• Addresses an issue where unneeded system data files might not be automatically deleted when available storage is low
• Fixes a thermal management issue that caused some displays to exhibit a green tint
• Fixes an issue where Exposure Notifications could be disabled for some users

Some features may not be available for all regions or on all Apple devices. For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222 

iOS 13.6.1 includes bug fixes for your iPhone.

• Addresses an issue where unneeded system data files might not be automatically deleted when available storage is low
• Fixes a thermal management issue that caused some displays to exhibit a green tint
• Fixes an issue where Exposure Notifications could be disabled for some users

Some features may not be available for all regions or on all Apple devices. For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222 

iOS 12.4.8 provides important security updates and is recommended for all users.

Some features may not be available for all regions or on all Apple devices. For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222 

Which latest update are you referring to? 

1. iOS Update? Which Version? Update your iPhone, iPad, or iPod touch - Apple Support
2. Carrier Update? Contact Carrier. Update your carrier settings on your iPhone or iPad - Apple Support
3. App Update? Which App? Contact App Developer? How to contact an app developer - Apple Support
4. Apple News Update? --> Read the latest headlines in the Apple News app - Apple ...

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.