Quote from Wikipedia - “The high rising terminal (HRT), also known as uptalk, upspeak or high rising intonation (HRI), is a feature of some accents of English where statements have a rising intonation pattern in the final syllable or syllables of the utterance.”
In other words someone makes a statement and it sounds like a question. Many people find it very annoying. I do not really have a problem with it.
I get annoyed with the opposite. Someone makes what appears to be a statement but they are actually asking a question.
I work in a bank call centre. The laws of the land are such that I cannot give any financial advice no matter how small. Most people seem to not know this and often fish for advice. I tell them the facts about some aspects of banking and at the end of the conversation the customer says something like “So the best thing for me is to take travellers cheques when I go overseas.” Long pause. I have to ask them “Are you asking me or telling me?”