It’s the name of a black grape variety. Noir means black in french.
Red Wines made from this grape are generally dry, light bodied, low in tannins, have good acidity & resemble aromas of red fruits like s/b & cherries. Also reds from PN will not be blended with other grapes, it will be made only from PN coz the flavours of this grape are v subtle, & if u try to blend it with another grape variety, its aromas/flavs will be overpowered. It’s a very difficult & fussy grape to grow, & needs a lot of TLC from the grape grower & the winemaker & that’s the reason these wines are generally more expensive than most others.