Ping is the time interval that it takes for you to send a packet of data out to a specific server. Ping time is measured in milliseconds or ms. 

For ping times the lower the number, the better.  A faster ping means your connection is more responsive which is important for people who play video games online where timing is important.

Latency is the time it takes a packet to do a round trip from your device to the server and then back again.