BIC stands for Bank Identifier Code. A BIC is sometimes called a SWIFT code - these are synonymous and mean the same thing.
These codes, which consist of 8-11 characters, are used to specify a bank when sending money internationally.
Where can I find the SWIFT/BIC code to top up my Plutus account?
If you're a user from outside of the UK, when you attempt to top up your account, you will be presented with your SWIFT/BIC code which is used when topping up your account. You can follow the guide to top up your account here