a tracert shows what "road" you choose to travel on to reach a specific server.
It display the latency (ping) to each router in the path, the router acts like crossroads.
sometimes a router can be overloaded with traffic, then you will see the ping goes sky high, but you cant be 100% sure, cos sometimes routers deprior ICMP packets (packets used to measuse ping).
I bet you can find a better explaination at google
VanBuren