To find the length of \( AB \) in triangle \( ABC \), we can use the relationship established by congruent segments and triangles. Given that \( DBE \) has lengths \( DB = 12 \) units, \( BE = 7 \) units, and \( DE = 14 \) units, and since \( \triangle DBE \) and \( \triangle ABC \) are likely congruent, we can use the information provided.
Assuming \( \triangle DBE \) is congruent to \( \triangle ABC \), then the corresponding sides will be equal; hence, \[ AB = DB = 12 \text{ units}. \]
Thus, the answer to the question is:
12 units.