You point to a humanoid corpse you can see within range with a drop of blood running down your finger and mutter an incantation. That corpse then rises as a zombie or a skeleton that follows your verbal command (no action required). That command can be to attack a creature, defend a place, etc. If given no commands, the undead creatures will only defend themselves.

The spell lasts for the full duration of the spell, or until this spell is cast again.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, you animate one additional undead creatures for each slot level above 3rd. Each of the creatures must come from a different corpse or pile of bones.