This appears to be a hand pointing up, which could have a variety of meanings. It could be used to indicate a question, to draw attention to something, or to suggest agreement. Depending on the context, it could also be used to indicate a positive or negative sentiment. For example, if someone were asking a question and the person they were asking responded with this gesture, it could mean they agree with the question or they understand it. Alternatively, if someone was making a statement and the person they were talking to responded with this gesture, it could mean they disagree with the statement or they don't understand it.
