Coconut oil is very different from most other cooking oils and contains a unique composition of fatty acids. The fatty acids are about 90% saturated. This makes coconut oil highly resistant to oxidation at high heats.
For this reason, it is the perfect oil for high-heat cooking methods like frying.
Speaking of cooking, coconut oil has a higher smoke point than other oils, which makes it safer to use in stir-fry and baked goods. When substituting coconut oil for butter, use 25% less oil than the butter amount.
This is because of coconut oil, unlike butter, is almost pure fat, and you need to account for that difference in your recipe.
And to compensate for the bit of moisture that butter normally gives off when it bakes, you may add just a dash of additional liquid to your recipes when using coconut oil, to balance out the moisture content overall.
But play with it a few times, and see what works best for your substitutions.