Newbie question about colliders and icons in editor

I have a character in a scene, and I try to let him run as a rigidbody. He has a capsule collider around his body
and does not fall thru the ground, at least.
What he does is getting instable, so he falls to the side after some time, and it looks like he has zero gravity.
Can someone explain me what the red and blue symbols are, around the shape?

 

They are gizmos drawn from the animator. They show where Unity IK positions are for the animator on the selected object. Collapse the animator component and the will disappear.

To make your rigidbody character not flop all over the place check the freeze rotation on the x and z planes on the rigidbody component.

 

Thank you very much !