Explanation:

By 2020, 90% of all people living with HIV will know their HIV status. By 2020, 90% of all people with diagnosed HIV infection will receive sustained antiretroviral therapy. By 2020, 90% of all people receiving antiretroviral therapy will have viral suppression.
A concept introduced by the United Nation’s programme on HIV/AIDS in 2013, 90-90-90 is a set of goals. The idea is that by 2020, 90% of people who are HIV infected will be diagnosed, 90% of people who are diagnosed will be on antiretroviral treatment and 90% of those who receive antiretrovirals will be virally suppressed. Viral suppression is when a person’s viral load - or the amount of virus in an HIV-positive person’s blood - is reduced to an undetectable level.
The strategy is an attempt to get the HIV epidemic under control and is based on the principal of universal testing and treating. What is central to “test and treat” approaches is that if one can identify people early on in their infection, and start treatment so they become virally suppressed, the onward transmission of HIV will be prevented and this will impact on HIV incidence at a population level.