Okay, I THINK I figured out how the filter thingy here works.

1. Click the Settings icon on the top right of a column
2. Scroll down to 'Advanced'
3. Put a text like this in the 'Filter out by regular expressions' box:

@.*bot\s|@someone\s|some word|more words

^ This would mute ALL toots that CONTAIN
1. usernames that end in 'bot' (but not ones that have 'bot' in the middle)
2. user @someone
3. words 'some word'
4. words 'more words'

Sadly it can't seem to filter out emoji like

In case anyone is curious:
'.*' means "any character 0 or more times"
'\s' means "any whitespace character", so that names like "@hungrybotanist" or "@someoneelse" won't be filtered

If you only wanted to filter out "word" but not "words", you could also put a '\s' after that.

Sadly, that WON'T work if it's at the END of a toot, since the ending apparently doesn't count as whitespace. 🤔
There might be a workaround for that, I'll have to look into that.

@Tobi Is it using RegEx for filtering? If so, \b means word boundry, so word\b should also get you word but not words.