The Select tool is used to select a subset of the input columns to pass through to downstream components.
Select has one input connector and one output connector. Connect an input step by left clicking on the input tool’s connector and drag onto the Select tool’s input connector. Connect an output step by left clicking on the Select tool’s output connector and drag onto a downstream component's input connector.
The configuration panel for the Select tool shows the input schema with checkboxes next to each column name. Initially all checkboxes are checked, meaning all the columns are passed through to the output. Uncheck any columns you wish to be excluded from the output.