"What have you been up to?" is a common English question that means "what have you been doing recently?". It is often used as a conversation starter or to catch up with someones latest news and events in their life. If someone asks you this question, you can respond by talking about something you have been doing that you are proud of or something that has been taking up a lot of your time. You can also give a brief update on recent events in your life. For example, you might say, "Ive been busy with work," or "Im just after coming home from holiday".