Latency is not related to the speed. We can get 1gbps even with poor latency.
Ideally, the latency within our country wouldn't cross 3ms on a fiber connection.
Latency can be measured using ping command. You may ask your friend about the ping times to various
google servers such as 8.8.8.8, 8.8.4.4 or g.co . There were already plenty of discussion on how poor those ping times were on Jiofiber network. Of course, it may have changed now.
Most gamers are concerned about latency (apart from the speed of the connection).