It is also strange to you that the column names in the table sometimes omitted some letter? It can make a sense, if it is desirable to have such a column hidden, eg. with helping calculations. How such column again to unhide? Have a look at this one minute video. If this guide has helped you, become a fan on Facebook and recommend this site to your friends, it can be useful for them too.
Please note that this tutorial is presented in czech language.