How is it called?

It is shown usually in the Pacific ocean -for available space-, I believe has something to do with (solar?) declination trough seasons, it is an elongated "8"

 

What does it mean ?

It's an analemma, that describes the "equation of time." The earth's orbit isn't perfectly circular, so the orbital speed changes over the course of a year, and that means that the sun's position at noon varies. The analemma describes the deviation.

 

http://www.analemma.com

 

some awesome pictures (taken over the course of a year at the same place and same time of day) at http://www.perseus.gr/Astro-Solar-Analemma.htm

Thanks !