You may receive an email from someone who claims they have a large amount of money and they need help moving it to the UK.  In return they will promise you half of the fortune.  The person will then ask you to pay a transaction fee to help the process along.  Alternatively they might ask you for your bank details so they can transfer the money into your account.

The sender may claim to be a barrister who is representing a wealthy client or someone famous in their homeland and will state that you need to act fast or they will get someone else who is willing to help as time is of the essence.

The email is a scam.  No such or person or fortune actually exists.  If you pay the fee you will not receive the fortune or alternatively if you provide your bank details they will steal all the money from your account.