It should actually be written, That sounds like quite a day. The meaning here is that the day this person has planned is full of a lot of things, and from the context here, a lot of positive things. This is a pretty common phrase to describe that your day was busy/eventful/full. It could be positive or negative. 'It's been quite a day...' 'Oh no, what happened?' "It's been quite a day, hasn't it?' 'It sure has! What a great day.' Hope this helps you out.