Based on the following reaction,XeO64- aq + 2F- (aq) + 6H+(aq) →  XeO3(g) + F2(g) + 3H2O(l) ∆G0<0It can be concluded that

Xe+8O6-4 + F- →Xe+6O3 +F02Since, ∆G0 < 0, hence it is spontaneous in forward direction. Oxidation number of Xe decreases, hence, it is an oxidizing agent; and oxidation number of F increases, hence it is a reducing agent.