I keep staring at this sudoku puzzle and can't seem to find the next move.
Is the next move a guessing move? I thought sudoku always has clear solutions, you just need to figure them out.
No you shouldn't guess. The puzzle has a unique solution. However, you can't continue unless you calculate all possibilities. Once you do that, solving the puzzle will be easy. I have added the possibilities below. If you want to do that on your own, don't look down.
Once you do that, I think the next step is clear:
others pointed out in the comments that it is unclear why that particular cell cannot have a 5. To explain, in the red column there are 2 cells indicated in blue. They have two possibilities: (3,5). No matter how the possibilities are distributed, any of the cells will definitely have a 3 and the other a 5. Which makes it impossible for any other cell in that column to have a 3 or a 5.
Additional explanation (requested by the OP):