Whether are just learning or are exploring a stitch dictionary for the first time, something you need to learn is how multiples work in knit and crochet pattern stitches.  

If you are learning a pattern stitch outside of a project, your instructions will most likely tell you to start with a number of stitches that is a multiple of something. The number of stitches you multiply by is the number you need to repeat the pattern stitch once.  For example, instructions might say to use an even number of stitches or a multiple of 3, 5, 10, or more. That means that, in order to do the pattern stitch once, you need that number of stitches.

If the instructions just say to use a multiple of a certain number, that's pretty simple, but it's often a little more complicated. Sometimes, the instructions will say to use an even or odd multiple of a number. Even and odd refer to the number you multiply by. For instance, 6 is an odd multiple of 2, because it is 2 times an odd number (3).  Likewise, 8 is an even multiple of 2, because it is 2 times an even number (4).

Finally, you will frequently see instructions that talk about a multiple of a number plus another number, a multiple of 5 plus 1, for instance.  This is an order of operations thing--you do multiplication before addition in multi-step problems. "A multiple of 5 plus 1", for instance, is not a convoluted way of saying "multiple of 6". Instead, it means that you use a multiple of 5 and then add 1 more at the end.  A multiple of 5 plus 1 could be 11 (2x5=10, and then add 1), or 56, or 101, for example.

The number tacked on to the multiple is what you need in addition to the pattern stitch itself to make the edges work. If we look at open filet in crochet, for instance, the basic pattern is to alternate double crochets and chains (a multiple of 2), but you need 1 more stitch at the end to keep from ending rows with a chain stitch. That 1 stitch at the end is a "plus 1".  Likewise, in knitting, you can't end a row with an increase or partway through a decrease or cable, and the extra stitches after the multiple keep that from happening. 

Because those extra stitches after the multiple are about having neat row ends, they usually do not apply when you adapt a pattern stitch for working in the round. Going back to that example of open filet, there is no ending double crochet when working in the round, so you can just alternate double crochets and chains over an even number of stitches, and attach the final chain to the first double crochet (the turning chain) of the round, and everything will line up correctly.