What does collecting the gold color circles suppose to achieve? I keep collecting them and nothing happens? Its not a power-up, and I do not see any benefit from collecting them.
If you are referring to the gold disks that float in the air that you need to jump for, those are a coin power up. They don't give any immediate bonus to your performance (unlike the magnet, shield, or boost powerups) but they are useful in that they can fill your bonus meter quickly. Such a successful jump and grab moves the bonus meter up about the same as multiple sets of low-level coins. Once the bonus meter is full, you can use your own power up of choice (shield in the illustrated example above, but boost and the Usain bolt ones tend to me more popular if they are available) sooner than if you didn't jump for that disk. It's not worth jumping for such a disk if it means you'll land in a gap and die or have a stumble or difficult move to stay alive, but frequent use of the powerups from the bonus meter is important to doing well in the game.
There are two main gold things in the game: gold and gold power-ups. Gold is the basic currency, used to purchase objects in the store. The gold discs floating in the air like a gem is the gold power-up, which gives you MONEY!
Presumably you're talking about gold. Gold is the currency used to upgrade things, purchase new characters, and unlock pretty much everything in the game. Grab as much of it as you can!