It depends. If you live in an area with a large number of bookstores or have easy access to major online book retailers, it can be quite easy. For instance, in big cities, it's likely that you can find it in a local bookstore or order it online and get it delivered quickly.
It can be easy if you know where to look. As mentioned before, Amazon and eBay are great online options. But you also need to consider factors like availability in your region, price, and the format you want (hardcover, paperback, etc.). Some versions of the 'Solo Leveling' novel might be more readily available than others, so it's important to be specific when searching.
In some cases, it might be a bit difficult. If you are in a remote area with limited access to bookstores and slow internet for online shopping, it could be a challenge. Also, if the novel is very popular and there is high demand but low stock, it may not be so easy to get your hands on. However, with a bit of perseverance and by checking different sources regularly, you should be able to buy it.