Greetings @ApisMellifera!
Siofra has you covered with some great tips and resources- I was trying to think of how I’d best word an answer to support what has already been given, and it’s pretty tricky to explain! I completely understand your confusion with visualizing how the moon moves through the zodiac signs 
Additionally, astronomers and astrologers disagree on some things with the zodiac signs/constellations (you may have heard about the debate over Ophiuchus), so note that I’m taking a more astrology-based approach here.
From Space: Zodiac Constellations and Zodiac Signs
The way I picture it is that, from Earth looking up at the sky, we see the moon and can watch it moving in the sky. This is because the celestial bodies (including us here on Earth) are in constant movement, revolving around one another- Earth is revolving around the sun, and the moon revolves around the Earth.
The Moon changes signs every two or two and a half days, and passes through all 12 signs of the zodiac every 27 and 1/3 days.
From We Moon
The Zodiac sign of the moon is based on which constellation the moon appears to be in- aka, which Zodiac constellation appears to be closest to the moon at any particular time. It changes to the next constellation every 2.5 days. And it goes through all 12 traditional zodiac signs within a 27.3 day period.
(Astrologers and astronomers, please feel free to correct me if I got any of that wrong!)
The astrological theory is that the sign the moon was in at the moment of your birth (as well as the position of all other planets in the skies) has an effect on your personality, life, future, etc. All of these influences can be read and examined through your natal chart 
Again, anyone is free to correct me if I got any of that wrong, but that is how I currently view determining moon signs! 
I wish you all the best with exploring your signs and chart, @ApisMellifera- good luck and blessed be! 
