When a cat rolls onto its back and faces you, it usually means it's trying to convey some important information. This could mean several things:

First, this is a way for it to show trust in you, indicating that it feels safe and comfortable around you. Rolling onto its back is a sign that a cat is relaxed and at ease, meaning it believes its surroundings are safe.
Secondly, it might be seeking your attention or interaction. The cat wants your notice and some affectionate interaction, such as stroking its belly. It could also be expressing feelings of satisfaction and happiness; it feels very pleased and wants to share this emotion with you.
In addition, rolling onto their backs can be a social behavior, an attempt to build a closer bond with you. However, it's important to note that in some cases, cats may roll onto their backs due to discomfort or pain.
If it exhibits other unusual symptoms, such as loss of appetite or lethargy, it is recommended to take it to a veterinarian promptly. In short, a cat rolling onto its back on the floor to face you is usually a positive sign, indicating its trust and affection for you. This is a way for it to build a close bond with you and express its emotions and needs.