Learn Hardcore German: Dieses Gerät wird jeden Abend gründlich gereinigt. - This device is cleaned thoroughly every evening.

wird is the third‑person singular present form of werden used here as an auxiliary verb to form the passive voice. It indicates that the action is being done to dieses Gerät by someone (the doer is unknown or unimportant).

How is the passive voice constructed here?

In German present passive you combine the present tense of werden with the past participle of the main verb. So wird + gereinigt (the past participle of reinigen) yields wird gereinigt (“is cleaned”).

Why use the passive voice instead of the active?

Passive voice shifts the focus from who performs the action to the action itself or its recipient. Here, the emphasis is on the device being cleaned every evening, not on who cleans it.

How would you express this sentence in the active voice?

You could say:
Man reinigt dieses Gerät jeden Abend gründlich.
(“One/people clean this device thoroughly every evening.”)
Or:
Jemand reinigt dieses Gerät jeden Abend gründlich.
(“Someone cleans this device thoroughly every evening.”)

What case is jeden Abend, and why?

jeden Abend is accusative. In German, time expressions without a preposition (answering “when?”) usually take the accusative case.