This is the 15838th most frequent Russian word.
прозрачными
"Прозрачными" means "transparent" (instrumental plural form).
In this sentence, 'прозрачными' is used as a descriptive adjective modifying 'стекла,' indicating a physical property of being see-through or clear.
Стекла в окнах стали прозрачными после того, как их помыли.
The windows' glass became transparent after they were cleaned.
Here, 'прозрачными' is used metaphorically to describe clear and obvious intentions, not a physical property.
Её намерения были такими прозрачными, что все поняли, чего она хочет.
Her intentions were so transparent that everyone understood what she wanted.
In this example, 'прозрачными' refers to the lasting property of clarity in selected materials.