If you have Blindsight, you can effectively see or sense your surroundings within a specific Range without relying on physical sight.
Within that Range, you can effectively see anything that isn’t behind Total Cover, or that typically follows Line of Sight, unless the source of the Passive Ability says otherwise, even if you’re Blinded or the Target is in Pitch Black or Magical Darkness.
Moreover, you can effectively see a Hidden or an Invisible Targets in the sense's Range.
It is worth to note that Caster cannot see beyond their Blindsight Range while in Pitch Black or Magical Darkness, and are effectively Blinded. All ranged weapon and Spell Attacks against them have ADV; the Caster has DIS on ranged Attack Rolls; and the Caster also have DIS on Attention rolls since they cannot see past their Blindsight Range. The Caster needs additional senses to see in Pitch Black, or Magical Darkness beyond their Blindsight Range.