Here is some info on the siren thing in the corner of your screen.
That indicates an Alert. An alert is a 2 hour contest on a continent to see
who can capture the most territory. Whoever has the most territory at
the end of the alert locks the continent for their faction and is given a
resource cost reduction for either MAXes (Hossin), vehicles (Esamir),
aircraft (Indar), or infantry consumables (Amerish). For example, if the
VS won an Indar alert the continet would be locked and their aircraft
would cost half the usual number of resources to deploy on all the other
continents. This bonus lasts as long as the continent is locked
(usually unlocks as more people log in or another one of the other 3
continents lock).
Edit: You also get bonus experience for fighting in an alert (30% I think?).
Edit2: Check this website for live alert info. Iām not sure if PS4 alerts are on here or not.