What is .Trash and .Trash-1000?

Have a look at How to prevent Ubuntu from creating a .Trash-1000 folder when deleting files from a USB flashdrive?.

According to the article, Ubuntu will create such folders when a file is deleted from a USB drive. Presumably this would allow a file to be restored if you accidentally deleted it.

In any case, the article offers the following recommendations to prevent a Trash folder from being created:

Don't use the delete button only (Otherwise the .Trash-1000 folder will be created)

Press the key combination shift+delete together to delete then Ubuntu won't create a .Trash-1000 folder. (Note: If you delete files and folders this way they are gone forever!)

For every mountpoint, Ubuntu creates a "Trashbin" as soon as you delete a file - so the file later can be undeleted.

The 1000 is the UID of the user that created the bin, so every user can have its own.