Definition: congruent means that objects have the same shape. It does not mean that they are 'equal', exactly.
People often confuse this word with 'equal,' but there is a small difference in the way that these two words should be used.
Equal should be used to relate the lengths or measurements of two sides, angles or parts of shapes.
Side AB is congruent to BC
$$ \angle A $$ is congruent $$ \to \angle B $$
The length of side AB is equal to the length of side BC
the measure of $$ \angle A $$ equals the measure of $$ \angle B $$