Is this plant sitting next to a sofa where you might have had some friends sitting and smoking? A friend's kid hanging out for awhile? This looks to me a cigarette burn. You have to send more pictures and information.
There are a few other spots I am able to see in your picture that have blackened. No big deal. Little tears or a munching insect could easily do this and turning black is this plant's defense. One day that black will just dry up and fall off.
Your plant looks too healthy to be susceptible to fungus/insects. Did you transplant this plant into this pot or did this plant come in this pot not too long ago. Did you use planting soil out of a bag? Or did you use garden soil?
I am stabbing in the dark here, grins. Really does look like a burn but then it really doesn't. Is there a center that is crispier than the edges? What is happening beneath that spot? Under the leaf? Is there a way you could send a picture of the entire plant? Give us information such as where this plant lives in your home, lighting? How long have you had this plant? What soil is in your pot? Your watering habits. Fertilizer?