Social point symbol is: 
Social points are earned by doing bonus actions, washing dishes at any tavern, playing minigames by clicking the chess table in a tavern or by fighting in the arena.
Bonus Times
Washing dishes at any tavern costs 5 AP per hour and gives 40 SP per hour. The max time you can work for is 10 hours, which will get you 400 SP. You can't do anything else while washing dishes and you will loose all AP you invested and don't get any SP in case you cancel the work before it's finished. Therefore you should only wash dishes before you logout for a longer time.
But playing minigames is a better use of your AP then washing dishes. While washing dishes will give you only SP, playing minigames will give you SP and xp. In general minigames even give more SP per spend AP, so don't wash dishes unless you don't have time to play minigames.
Social points usage:
Social points can be used to upgrade your house , buy things for your house in house editor or even donate to the guild to upgrade the guild house.-except the first 1750
