NIKKOR: Nikon's brand name for all their lenses.
Z: For Nikon's mirrorless cameras.
S: Subliminally suggests sexual satisfaction. It has no other meaning; Nikon and car and every kind of marketer have been using letters like "S" and "X" in model numbers since the 1940s for this same reason for just about everything. Nikon called their first rangefinder lens mount in 1946 the "S" mount, then went to to the "F" SLR mount in 1959, used "S" again when they updated their AI lenses to AI-S in 1983, and here it is again.