>>3471085just think of it like this
lower f/(number) means that your light opening is larger and lets in more light but it also means less depth of field and less objects that are in focus
higher f/(number) means that your opening is much smaller and lets in less light but has an advantage of having more things be in focus
usually the sweet spot for lenses is about f/5.6 and f/8 for optimal sharpness but sometimes f/8 is not enough to get everything in focus so you can go down to f/14 to achieve that.