A percentage is a certain number of hundredths of something. For instance, if you have a hundred sheep, and you give five of them to the government for taxes, that is five percent (5%). If you have only ten sheep and you give five of them for taxes, that is 50%. Can you see why?
(Because 50 is half of 100, just as five is half of ten; fifty hundredths is the same as five tenths.)
If you have a hundred pounds of wheat, and you give five pounds of wheat to the government, that is also 5% of your wheat.
More about percentages
Bibliography and further reading about percents:
Delightful Decimals and Perfect Percents: Games and Activities That Make Math Easy and Fun, by Lynette Long.