Hi! I'm happy to help!
Fractions are wholes that are split up. When you split the whole into more pieces, the pieces are smaller.
Due to the fact that 5/12 is split into more pieces than 5/11, and they have the same amount of pieces, 5/11 would be larger because of bigger pieces.
5/11 is bigger because it has bigger pieces.
I hope this was helpful, keep learning! :D