"Westoppenhetafvalindevuilnisbak."

• het vuilnis = the garbage
• de bak = the container, the bin
• het vuil = the dirt

-nis is a suffix, not a well known one, I don't know what it means or how it modifies meaning but it is used in e.g.

• de gevangenis = the prison (an interesting word now that I think of it: vangen = to catch/to capture, gevangen = caught/captured, also the outdated het gevang has the same meaning as de gevangenis)
• de gevangene = the prisoner
• de kennis = the knowledge
• kennen = to know
• de duisternis = the darkness (duister is usually an adjective, meaning dark, sinister)
• de betekenis = the meaning
• de hindernis = the obstacle

In a way it still means that. The way I think about it is, you're moving the trash (from where ever it is) and "stopping" it in the trash can.