Hi @gungho, this is when for example you are doing post and want to share the Payout with someone, like I did for the tutorial of Jorge that I used for my drawing and share the payout with him, for that there is a button called advance setting:

This is how it looks on Steemit:

Here is how it looks in AVLE:

At the end we both receive 50% of the post. You can set up any % that you want to share. Normally as default it set up to 100% to the Author.