I would like to know the clear definitions of Population, Intervention, Control and Intervention shortened as PICO and how is it used in a systematic review?
These terms are used to define the inclusion criteria and exclusion from the review. For each of the domains (PICOTS), you define inclusion criteria for the review and exceptions to them as exclusion criteria. P - population / study group / patient / problem; I - intervention / drug; C - comparison / control group; O - outcomes (in which domains you want to measure results); T - time frame (it is about limitation, for example, to new sources); S - settings / study design (eg type of research sought, publication language and other "technical" details of the reports sought). Once you're done with this, you apply these findings to your search strategy.