Why does pool latency matter? I often read about latency and ping.
I am programmer and I understand what latency and ping is.
But I do not understand why miner can't process block with certain delay. 
Why do 10ms or 100ms matter?
Latency of connections between nodes matters when mining because, essentially, a valid block found that reaches the highest number of peers first wins that block height.

For example, if miners Alpha and Beta both find within a few milliseconds of each other, their incentive to push that block around to connected clients as quickly as possible is that they get their block on the chain first and thus are able to claim the reward.

More technically, if we're currently at block height 10, and miners are hashing to find a solution that will become block 11, and Alpha and Beta both find a block, they can both claim it to be block 11. However, it only actually becomes block 11 when 51% of nodes believe that a certain block is the 11^th block. The other block, the valid block that lost the exposure contest, becomes an orphaned block, and gets pruned when the height 12 blocks start coming in.