When choosing a pick, think about the style of music you are mostly going to play. As a beginner, you probably will be strumming a lot, so you may want to get a more flexible pick that will play a lot softer. If you play a lot of single string runs, solos, and heavy metal/thrash then go for a thicker pick. Thicker picks will make your strings (especially on acoustic guitar) ring louder.
The gauge numbers to me are mostly arbitrary. I just get 2 or 3 that flex… a couple that flex less, and a couple that are stiff. I can play and pick with just about anything (or nothing) so I am not too wrapped up in being tied to a certain number or brand. Once you find what you are comfortable with, then the numbers and brand will help you remember.
Again, I just keep an assortment around. If I am tracking (recording) then I pay a little more attention to the pick, but for just playing around and practicing, it really doesn’t matter too much to me. I would say typically I play a stiffer pick with my electric guitar and a more bendy with my acoustic.