now, here, this, time, year
玆 centers on the present moment or location: now, here, this. The time and year senses extend that idea to the current time or year.
玆 is a duplication of 玄, which originally depicted a twisted thread and later came to mean dark or profound. The doubling likely intensifies the idea of something immediate or present, but the exact historical development is uncertain.
Two 玄 side by side look like a pair of dark, profound threads twisted together. Imagine holding them right now, here in your hand—this is the present moment.
For シ, picture a sheet of paper with 'now' written on it: sheet -> シ, and the sheet is right here, this moment.