A share reflects the amount of usefull work you've done. Since the work is divided over several (thousands) other miner the resulting coins are shared between everyone depending on how much each have contributed to the work. Everyone that finds anything during the current block will get a share of the profit. The value of the share depends on the total value found in the block and on how many to split the profit between.
See also What is a share? What is share value? in ypool FAQ.
Depending on the lenght of the found chain, you get a share value for the current round. The share values are :
|Length of chain||Share Value|
|10ch (Block solving)||
Table reflects values given after Jan 13, 2014.
After the round is completed, the new XPM (currently 9.52 XPM) are splitted by the contributed share value. Keep in mind that your Share Value isn't used only for a single round but for 160 rounds. The block yield is calculated by the "Full share value per block".
Here is an example regarding XPM. In the graph "Share value earned..." I see that I got a 0.07 share value, which, according to the table above means that I did find a 7 length chain.So far it does not tell me much except that it was no
Later I go in under "Stats, Personal stats" and look at the "Share value earned during individual round" and there I find this 0.0700 share in the graph
Either looking under the graph or howering above the point I can see the block number to which this share belongs. In this case it belongs to block number 305848.
Then I goto "Stats, Blocks found" and look up the 305848 block
Here I can see that the total value of this block was 10 XPM, The share value is 120116.96 (is this the total number of shares in this block?) and at which time it was found. Unfortunately it also says that it was "Orphaned" which means that the value is zero (someone else than Ypool mined that block).
To see the value in XPM (for now, we ignore the fact that this block are Orphaned and thus are worthless) we click on the block id "305848" to get to the details.
When the page has loaded I use the search box to find my name, which shows this: