Perhaps the most relevant statistic, in the upper left corner we see the current block number, showing the current length of the Ethereum blockchain.



Below it we see the time between blocks for the last few blocks. As you can see this number fluctuates, but should average about 15 seconds. This average block time is displayed prominently at the upper right, and to the left of the average we see how long ago the last block was produced.



To the right of the block number and below the block time graph we see the Uncle display. An uncle is a block that was mined but wasn't included in the blockchain, usually because someone else mined a block slightly faster. Having some uncles is normal but too many uncles could signify that blocks are propagating too slowly in the network. A more direct measure of this propagation is the "block propagation" graph. A healthy network has more bars to the left, signifying that blocks are spreading quickly across the network.