This is something that helps you finish construction upgrades and knowledge upgrades faster.
When you start an upgrade you are offered a green Help button which puts your project on the help needed list.
If there is anyone that needs help a Helping hand icon is displayed above Loki's chest and by pressing this button you come to the help needed list. You can also access the list from Clan menu and select Help Clansmen.
In the default tab, Received requests, you see all current help requests and how many that have already given their help.
Tips: Take some time to see what projects your clan mates are doing, it gives you a feeling of what your friends are in the game progress.
Buy giving help you earn 10 Loyalty points and 10 Prowess points for each help given (but 100 points during the current 24h period). The clan mate who get your help will get the time left on his/her project lowered by 1% of the time left (or minimum by 1 minute). Depending on that person Palace level he/she can get help from up to 25 other clan members. Note that the boost is calculated on the time left when you press the button, so the quicker your are to give the help, a bigger speedup will be applied.
On the 2nd tab you can see your own current projects and how much help these have received.
Beware: If you change clan, your current projects will not receive more help.