How exactly does the point defense drone from the Raven work?

Does it intercept shots from all ranged units or only specfic stuff such as turrets? And does it intercept multiple shots from many different units?

 

hold on the icon for it when selecting raven will shot what it blocks

 

only projectiles. defined as a ranged attack that has an object flying towards the enemy. marine bullets, for example, are instant-hit, so PDD doesn't block them. ATA missiles, grenades, hydra spines, etc. will be blocked.