The Bow is a tried and true classic weapon, but its usability always comes down to the Arrows. When you're just getting started, you may be wondering how scarce or available they are, as this often varies between different games. So, allow us to explain!
Starting off we have the easy and obvious answer, the Shop. Here you can purchase Arrows for the low cost of 2 Tul a piece, up to your maximum capacity (which starts at 30).
Given how affordable they are, it's a wise idea to restock your supply every time you head back to the Kingdom. Don't forget, you can easily teleport back and forth before entering a new dungeon.
Breakable Objects
If you want to avoid extra trips to the Shop, be sure to smash any breakable objects you encounter. Sometimes you'll find Arrows hidden inside, along with Bombs and other goodies.
Monsters
Defeated enemies occasionally drop Arrows on-death, providing you a convenient way to acquire them on the go. It's worth noting that you do NOT need to have shot them with your Bow for this to happen.
How to Expand Your Arrow Capacity
By far the best way to accommodate the Bow is to obtain a Quiver. This increases the maximum number of Arrows you can carry, allowing you to hoard a much greater supply each time you set off.
Without spoiling the details, you can find your first Quiver by completing one of the earlier Side Quests. This will increase your capacity from 30 to 45, which is a considerable boost from where you started.
I'll leave the remaining Quivers for you to discover, but just know there's more than one!