Sekiro: Shadows Die Twice changes some things around when in regards to dying, compared to FromSoftware's last few titles. One way in which it does this is through the possiblitiy of activating the Unseen Aid mechanic, which makes falling in battle less punishing.
Here's all we know about how to activate Unseen Aid and what it is.
How to Activate Unseen Aid
Death is a common occurence in FromSoftware's titles and, while there's plenty of it in Sekiro: Shadows Die Twice, the Unseen Aid mechanic can make it hurt a bit less. Usually, Wolf loses half his sen and Skill Experience upon death. What the mechanic essentially does is provide a chance of that simply not happening. When it triggers, Wolf will simply respawn at a nearby Sculptor Idol while holding onto all his sen and Skill Experience.
As handy as it can be, Unseen Aid cannot be activated manually, being, instead, entirely chance-driven. With a maximum cap of 30% and a minimum cap of 5%, it's up to the RNG gods to be merciful with you. What players can do, however, is make sure the percentage stays capped, which requires dipping into Sekiro: Shadows Die Twice's Dragonrot and Resurrection mechanics.
Aside from simply respawning at a Sculptor Idol, Wolf can also resurrect immediately after dying, holding onto his sen and Skill Experience but spreading Dragonrot to others. As people get infected, Rot Essence items appear in his inventory which decrease the likelihood of "Unseen Aid" triggering. The more Rot Essences you have on you, the lower the chance of receiving Unseen Aid upon respawning. The only way of raising your chances of Unseen Aid activating is by curing Dragonrot. There are, however, only a limited amount of cures in Sekiro: Shadows Die Twice, so you'll have to tread carefully.