The Angle-Side-Angle Postulate (ASA) states that if two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the two triangles are congruent
From the picture:
∠A ≅ ∠F
∠B ≅ ∠E
AB ≅ EF
then, by ASA postulate, the two triangles have the same size and shape (they are congruent)