While the following examples are given for filters, the same operators and functions can be used with formulas as well!
Equal vs. Colon operators
You're probably familiar with using the equal sign to filter results. You can use a search of the format filter column_name = "search term" to return results where the data in that column exactly matches your search term.
Similarly, you can use the colon operator to return results where the data in that column merely contains your search term.
Just as you can filter for certain results, you can also filter for not certain results.
If you have a sheet where values are blank in a column, you can filter on that.
Use filter isblank(column_name) to show all rows in which that column is blank
Or filter not isblank(column_name) shows all rows in which that column isn't blank.
Perhaps you have a column with a required value missing, giving you an error.
Use iserror(column_name) to show only the rows with errored cells.