http://knittingfever.com/noro/pattern/04-mosaic-shawl/

I just down loaded this pattern on knitting fever. In looking at the pattern I don’t know the difference between Sl 1 and Sl. Also I am unsure how to tackle alternating colors. Under notes it says one row of chart represents 2 rows of knitting. Not sure what that means. I am at a lost with the chart. I know there are many questions about this pattern but I really want to make this. I am an visual learner and what I am reading is very confusing. Can you help me with this pattern. Thank you RIta

Welcome!
Patterns tend to use S1, Sl 1 and Sl interchangeably. Sometimes it’s a difference in fonts, sometimes just inconsistency. Unless your pattern defines Sl 1 and Sl differently, assume they mean slip one.
http://knittingfever.com/noro/pattern/04-mosaic-shawl/
Here’s a video for mosaic knitting that may help. The finished product looks much more complicated than the actual knitting.

Charts often give only the right side rows. I don’t have your pattern but probably for the purl side rows, you should work the sts as they present themselves: purl the bumps and slip the slip sts from the previous row. The video may help with this.