Giro means a turn in Spanish from the verb girar to turn. ( ‘Hacer un giro’ – to make a turn ). In tango ‘giro’ usually means to take a turn round one’s partner. The expression ‘giro pattern’ typically means these four steps: ‘Forward’, ‘Side’, ‘Back’, ‘Side’, so that the follower travels around the leader in four even, equal, precise steps that form an even square/ diamond or circle around the leader. The ‘Giro’, or journey round one’s partner can be started with any of these steps , but once a giro is clearly indicated and led the follower will continue with the giro pattern until led to do something different ( eg, speed up , slow down, stop, change direction ).
[For exercises and practical tips go to ‘Teaching notes’.]