It is the phrasal verb. It means that you haven't seen somebody for a long time and want to tell a lot of interesting things, for example. This is from a book: catch up (with somebody), catch somebody up = move faster than somebody in front of you so that you reach them For instance: I'm not ready to go yet. You go on and I will catch up with you / I'll catch you up.

Lena ^^'s answer in the comments is close to correct. You don't necessarily have to meet though - you could 'catch up' with a phone call. In your case it would be 'tell you about what happened on my holiday'. Bogdan's answer is confused. His definition is almost correct ( 'catching up' isn't necessarily interesting) but the example he gave is a completely different meaning.

to "catch up with someone" means to see someone and exchange news/events from both your lives since you last saw one another. https://forum.wordreference.com/threads/ill-catch-up-with-you-later.186696/