{{ 'hello' | upcase }}
uses the upcase filter, when inserted into an options block it will render HELLO. You can string multiple Liquid filters together, with the expression processed left-to-right.
{{ "now" | date: "%Y-%m-%d" }}
Sample result: “2018-04-24”
Reference
{{ .my\_array | size | times: 10 }}
Sample result: 50
Reference