A Rollover is a movement from a 401k, 403b, or similar retirement account to an IRA. A rollover is coordinated primarily by the customer themselves with their existing retirement custodian. Typically funds are sent by wire transfer, which is the recommended method. Funds can also be sent via cheque, however, this is significantly slower than sending funds via wire transfer.
Before completing a rollover you must liquidate your other retirement account to cash (USD).