Hello
Please check https://www.teachoo.com/8790/2820/Corresponding-parts-of-congruent-triangle-(CPCT)/category/Congruency-of-triangles/
Congruent parts of congruent triangles
which means the when the figures are congruent their parts are also congruent
Example:- triangle ABC is congruent to triangle DEF
therefore by "cpct" AB=DE ANGLE A =ANGLE D..ect.