Be careful not to shove too often, it can invite your opponents to call with wider ranges, so use them wisely.
You may be in a difficult situation when you don't know what to do in a short-stack situation. The push or fold charts are there to help you make the right decision at the right time.
It uses Nash equilibriums to tell you what to do depending on the number of big blinds you have left.
Depending on the number of big blinds you have left and your position on the table, you can tell from these tables whether you should go all in or not with the cards you have in your hand. Beware, these tables are not an exact science, it is up to you to adapt them to your table and also take into account the stacks of your opponents.
These tables are to be used preferably when the players before you have folded. This may be useful for stealing chips, but you'd prefer to get paid when you're at the top of the range and fold the remaining players when you're at the bottom of it.