SOL is Mars solar day, also known as Martian day. A sol is slightly longer than an Earth day. It is approximately 24 hours, 39 minutes, 35 seconds long. A Martian year is approximately 668 sols, equivalent to approximately 687 Earth days.

The number which you see after SOL is the total day of NASA’s Curiosity rover on Mars.

Mars is so far away in fact that it takes signals quite a long time to get from the Mars back to Earth, On its close approach distance between Mars and Earth is 54.6 million kilometers.

No, but there is evidence that there was once water on Mars, it does not rain there today.

Not exactly, Mars is too cold and dry, but scientists are trying to find out is there any way to do so.

Yes, but very less in volume only 0.174% of Martian atmosphere

Yes, but almost all water exists as ice on north pole.