Stands for "First In, Last Out." FILO is an acronym used in computer science to describe the order in which objects are accessed. It is synonymous with LIFO (which is more commonly used) and may also be called LCFS or "last come, first served."
A stack is a typical data structure that may be accessed using the LIFO method. In a stack, each item is placed on top of the previous item, one at a time. Items can be removed from either the top of the stack (FILO) or from the bottom of the stack FIFO. You can imagine a FILO stack as the paper in a printer tray. Whatever paper you place on top of the existing paper in the input tray will be accessed first.
FILO is not necessarily a "fair" way to access data, since it operates in opposite order of a queue. Still, the FILO method can be useful for retrieving recently used objects, such as those stored in cache memory.