control
The word 'controllo' is used in Italian in similar ways as 'control' is used in English. You can use it to refer to the power to influence or direct people's behaviour or the course of events, like in 'il controllo della situazione' (the control of the situation). It's also used to refer to the activity of monitoring, like in 'controllo della qualità' (quality control).
I'm performing a security check.
The Italian verb 'sto facendo', present tense of 'fare', is used here to express an action in progress, 'a security check'. 'Un controllo di sicurezza' is a compound noun where 'controllo' means 'check' and 'di sicurezza' means 'security'.
My job requires a lot of control.
The phrase 'Il mio lavoro richiede molto controllo' describes a job that needs a high level of careful monitoring or management. Here, 'controllo' is used to express the need of detail attention and regulation.
You need a regular medical check-up.
In the phrase 'Hai bisogno di un controllo medico regolare', 'controllo medico regolare' is a compound noun where 'controllo' stands for 'check', 'medico' for 'medical' and 'regolare' means 'regular'. This phrase advises the need for regular health monitoring.