It sends a strong message. Usually, it conveys that you have a strong sense of obligation but are not really invested or passionate about whatever it is you are late for. It could also be an indication of poor planning, disrespectfulness, inability to prioritise or poor time management skills.
Fortunately, you have an opportunity to remedy all these perceptions clouding the opinions of the person you are late for. Your first interaction will affirm or deny their opinions. Life happens to all of us. We get curve balls and unforeseeable situations.
Communicating it clearly and humbly alleviates many of their doubts.
Backing it up with respect and trustworthiness going forward secures it.