One of the biggest mysteries surrounding the titular Mandalorian in Disney+'s The Mandalorian series is whether or not he takes off his helmet - and episode 4, "Sanctuary", proves that he does indeed do so, but with certain exceptions. The Mandalorian culture is unlike anything else in the Star Wars franchise. Hailing from the planet Mandalore, the Mandalorians are a unique breed of warriors who have wielded ancient weapons, crafted incredibly strong armor, and defeated notable foes. All of this extends in some way into The Mandalorian show.
It's been confirmed that the main character was a foundling - an orphan - who was taken in by the Mandalorians after his parents were killed during the Clone Wars. A handful of flashback scenes from the first few episodes of The Mandalorian showcase some sort of droid attack on the Mandalorian's homeworld. Whether that planet is Mandalore and if the attack was really the Siege of Mandalore remains to be seen, but regardless, at some point after the attack, the young child was rescued by the Mandalorians and later assimilated into their culture. Since then, he hasn't taken off his helmet. Sort of.
About midway through The Mandalorian episode 4, "Sanctuary", the Mandalorian tells a young widow (Julia Jones) that he removed his helmet one day before. However, he hasn't removed his helmet in front of another person in decades - since the time he was taken in by the Mandalorians. As he tells her, "This is the way." Shortly after this conversation, the Mandalorian removes his helmet off-screen so that he can eat, but no one else is around to see his face. This solves a mystery about the main character and the Mandalorian culture but brings up another question.
In the previous episode, "The Sin", the Mandalorian tells the Armorer that he's never removed his helmet. And since Mandalorians are always seen with their helmets on, except for those in the Star Wars animated shows, this made people wonder if they actually wear their helmets at all times. The answer to that question is both yes and no. Going based on what's revealed in The Mandalorian series, Mandalorians do remove their helmets when they are alone but never when they are in the company of others, possibly even people they are close with.
Given that the Mandalorian culture is one of pride and honor, nothing physical happens to them when they remove their helmets in front of someone else. Instead, they lose the privilege of putting it on again. This is what the Mandalorian tells Cara Dune towards the end of the episode, which she appeared to believe was a bit ridiculous. To some, it may be an anti-climactic reason for Mandalorians constantly wearing their helmets, but once again, knowing their culture, it's actually understandable.
Right now, The Mandalorian series is treating viewers in the same way that the Mandalorian character treats everyone else. Audiences may not get to see the Mandalorian's face on-screen for some time, but at least the show has opened up the option for it to happen eventually. Before the show premiered on Disney+, the big question was whether or not people will even see Pedro Pascal's face as the Mandalorian. While there's no answer for that question yet, the show hasn't wasted any time in setting up the possibility down the line.