What are these symbols?

I have qtVLM and the Caribbean chart pack. In the image below are two yellow trapezoids which I have circled in red.
What are these?
In one of the circled areas, what does 'Laure' signify?

What does the number next to it (41040) signify?
I right click, select vector chart elements and get a dialog that says it's a special purpose buoy
FL (4) 20s
So FL means fixed light
Does (4) mean visible for 4 miles?
what is happening at 20s?

These are special purpose buoys, in that case ODAS (Ocean Data Acquisition System) which you can learn via the pick-up report (right-click, vector chart elements). Laure is just the name of the buoy, as is 41040

FL 4 20s means a Flashing Light visible at 4 miles flashing every 20 seconds.

A Fixed Light would be just F
See this post for a similar question:  www.meltemus.com/index.php/en/forum/qtvl...hart-packs-rncs#2503

Btw if you load weather buoys data (right click, weather stations download), you will even learn about the data the buoy is collecting

 

thank you for that. I could reproduce this info for marker 41040 but not for the others (41041 or 41300 or Laure) Does this mean there is no data for those markers? 

I suppose the data for these stations is not published by NOAA.