what does latency indicate?

Latency is the time it takes for data to pass from one point on a network to another. 

latency is measured between a user's device (the "client" device) and a data center.  

The causes of network latency are distance 

Latency is a synonym for delay. 

In telecommunications, low latency is associated with a positive user experience 

Network latency can be measured by determining the round-trip time for data to make a trip.

latency be reduced. Use of a content delivery network (CDN)

CDN stores the data closer to end users, so it does not need to travel as far to reach them.