=FILTER() returns a filtered version of the source range, returning only rows or columns that meet the conditions you specify. In other words; you select a range of data → you filter that range → and then present the filtered version of that range.
For example, in the list below we use the =FILTER() function combined with the =NOW() function to filter items with dates from the last 7 days.
=FILTER(A2:A,A2:A>=(now()-7))
Glide has it's own Filtering capabilities which make filtering lists much easier. However, there are some things you can't do in Glide that you can do with the =FILTER function in sheets.