a charge is a legal claim on a property
for example if you were to borrow �50000 on a mortgage from the bank on a property worth �100000, the bank would have a charge on the property so that if you sold it, or died, the bank would have claim on the first �50,000
if you then decided to borrow another �20000 of the equity from say, norton finance, they would hold a 2nd charge on the property, i.e. bank gets first pickings of their �50,000 and then Norton Finance would get their �20,000
HOPE THIS HELPS