By default, when you add multiple tags to a filter, you are asking Dash to show you assets that match all of the chosen tags.

You can ask Dash to ignore specific tags instead. This works on the following field types:

For example, in this filter, I have added two plant names to my Plant Name tags filter, meaning Dash will do a search only for assets that match both of these names:

By hovering my mouse over a tag, I can hold the Option/Alt key on my keyboard and click the tag to invert it, meaning it is now a "not" filter criteria.

When a tag is inverted, it looks like this:

Dash will now return assets that match the "Birds Nest Fern" tag but do not match the "Aloe Vera" tag.