Water is a good solvent of ionic salts because

Water is an excellent solvent for ionic salts because its molecules are polar: one side has partial negative charge near oxygen and the other side partial positive near hydrogens. These dipoles orient around dissociated ions to form hydration shells—oxygen faces cations and hydrogens face anions—stabilizing separate ions in solution and preventing them from recombining [1]. In addition, water’s high dielectric constant (a consequence of its polarity) reduces the electrostatic attraction between oppositely charged ions, making ionic dissociation energetically favorable and enabling salts to dissolve readily [2]. Thus the molecular dipole and resulting hydration and dielectric effects explain why water dissolves ionic salts effectively.

Sources

1. [1] https://www.usgs.gov/media/images/water-molecules-and-their-interaction-salt
2. [2] https://www.acs.org/middleschoolchemistry/lessonplans/chapter5/lesson3.html