The answer depends, as many Star Wars questions do, on whether you're looking at Canon or Legends, but both have some of the same points. Since you're asking in regards to The Mandalorian, I'll give the Canon one first.
Beskar in Canon is a particularly strong type of steel used, or at least produced, almost exclusively by Mandalorian smiths. It's a traditional material used most commonly in the production of a Mando'ad's armor but weapons and other items may be made from it as well. Its extreme durability (being all but invulnerable to blasters and lightsabers, for example), makes it highly prized by Mando'ade, though not all armor is made from it. The Tribe in The Mandalorian seem to be considerably more spiritual or even religious than other depictions, to the point that they outright declare weapons to be "part of their religion", so they have a considerable respect and deference to the use of Beskar. It should also be noted that by the time of the TV show, the Empire has taken over Mandalore and routed production of Beskar into its own stores, as well as stolen quantities of it as seen in the show, in effect stealing Mandalorian cultural heritage (the forging of Beskar was considered an art and secret among the Mandalorians). There may be an analogue there to the Third Reich stealing all manner of items of cultural and religious (and personal) significance from Jewish families et al prior to and during the Second World War.
In Legends, Beskar is slightly different. Most notably, it's not an alloy or steel as it's depicted in the show, but a unique form of "iron" that was only found on the planet Mandalore. (While it could be alloyed with other materials to enhance its properties; it didn't have to be.) As such, only Mandalorian smiths had the knowledge and resources to forge it and it was consequently very rare throughout the Galaxy and indeed on Mandalore itself. As with Canon, the Empire had a vested interest in acquiring quantities of the material and initially entered into a treaty with Mandalore for exclusive mining rights and information on how to forge it in exchange for considerable contracts with the MandalMotors shipbuilding firm. However, the Empire's rule over Mandalore became increasingly tyrannical and ultimately resulted in the enslavement of the Mandalorians and the strip-mining of the majority of the world's Beskar veins. It was not until after the Empire fell that Mandalorians were able to discover new deposits of Beskar and resume their cultural traditions regarding the metal; presumably, Beskar throughout the Galaxy was returned in one degree or another to Mandalore for use by its people.
Both depictions of the metal were highly valued by the Mandalorian culture, primarily because as warrior races, it was a traditional material that was one of the key reasons for their strength in handling enemies up to and including the Jedi Knights. Likewise with both depictions, the Empire's theft of the material from Mandalore and its eventual subjugation of the Mandalorian people made recovering Beskar a matter of regaining cultural heritage that was nearly destroyed. However, Mandalorian culture in Canon is still somewhat sketchy; for example, whether or not The Tribe represents a more widespread system of belief or ideology among the Mandalorians at large or is just relegated to that particular group (evidence from other Canon sources would indicate the latter, such as the rule regarding removing one's helmet) is somewhat unclear.