Simplify the following text for a Grade 5 native English-speaking person.
Original: In archaeology , a biface is a two-sided stone tool and is used as a multi purposes knife , manufactured through a process of lithic reduction , that displays flake scars on both sides .
Simplified: In archaeology , a biface is a two-sided stone tool , made by chipping off flakes with another tool . It shows flake scars on both sides .