To select text, enter visual mode with one of the commands below, and use motion commands to highlight the text you are interested in.
Then, use some command on the text.
The operators that can be used are:
!filter through an external command
=filter through ‘equalprg’ option command
gqformat lines to ‘textwidth’ length
|Start Visual mode per character|
|Start Visual mode linewise (horizontal selection)|
|Start Visual mode columnwise (vertical selection)|
|Exit Visual mode without making any changes|
|Visually select inner word (where the cursor is positioned)|