Bounties are offered by ICOs as a way to reward you for promoting/marketing their ICO for them to help them reach a wider audience.
One of the easiest and therefore lowest rewarding bounty for a newbie or jr member(most don't offer much to newbies) here on BTT is a signature bounty campaign. You need to read the rules throughly of each bounty campaign to ensure you meet the requirements. Especially for larger bounty campaigns that require you to repost/retweet/like everything from the ICO etc every week while the ICO is running for example for them to deny you would kind of suck.
Easiest one by far is the signature campaign bounty. I'd recommend that once you hit Jr Member. But if you like an ICO's project and have a good social media audience (usually one of the requirements of any social media bounty) then just read up on them on each ICO's ANN thread to see if its worth your time and effort to complete for the reward you can receive.
If you have time and are multilingual - there are also translation bounties you can reserve and complete.
A few nights ago I completed a validation bounty for a project that involved checking a few Facebook profiles to see the aging of the accounts to ensure they were created prior to a specific date as part of the sign-up rules.
There are also bounties for blogging, vlogging, logo design, etc. Anything and everything the ICO might not have the time or expertise for they can potentially outsource via bounties if they want to.
Once you have been around for a few months these things won't be so unfamiliar. But just remember, one of your biggest resources - is your time. And its valuable so don't give it away for free

Thank you for the information, I would just like to know how to spot a good ICO as when I check on the bounties is really confuses me I already get how the social media bounty goes along with the signature bounties as taken from your answers however I really do not know how to spot a good ICO.