In 2013, when the Bitcoin price was just showing a strong downward trend, there was this one Bitcoiner. He wrote a post in the Bitcoin forum of bitcointalk.org in which he made it clear that he would not sell his bitcoins because he was aware that his trading skills were very limited and that he was better off just holding the bitcoins.
He wanted to give this post the title "I am holding". Since the man was drunk, as he wrote himself in the post, "holding" became "hodling". Many users felt the same way and the post quickly became popular. Within a very short time, a meme was born and hodl has become a common investment strategy to protect oneself from emotional fluctuations, which can happen when the Bitcoin price is on a rollercoaster ride. You could also just call it saving, but when you hodl, it's just much more in style. 😉
Also. So. HODL your satoshis!