Hi, welcome to KH. Assuming you marker is on the needle between two stitches, you just move it to the other needle. If you look at the top of the page here you'll find a Glossary button. There are lots of knitting abbreviations there, some have videos attached.
What are you making? If you have any problems, this is the place to come for help. We have some of the best knitters you'll find here. They're great.
You're welcome. I found this site and was amazed at how much help I got, and how quickly. I'm not a terribly experienced knitter but I've learned a lot here and gotten so much help I like to be part of the fast response time when I can. I think we all encounter abbreviations that are hard to interpret. The glossary here gets lots of use. I hope you stick around and let us know how your sweater is coming along and we just love pictures.