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.
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.