In this article, the author writes:
This galaxy is so distant that it would have been invisible without the gravitational lensing effects of a large galaxy cluster called Abell 1689, located nearly 2.2 billion light years away in the constellation Virgo. The cluster’s enormous mass acts as a natural telescope by bending and amplifying light from objects behind it, like A1689-zD1.
To me this doesn't quite sound the same as what a telescope is doing.
My question is: How can a galaxy in-between our view and the galaxy behind it have a 'lensing effect'?