Q.My Philodendron Hastatum Developed A Spot, What Can I Do?
I had just gotten this plant a few days ago and it was already a bit uncared for when I found it. While I have a bit of plants already Please know I\’m still learning, and none are like this one so I want to find out the best way to help from anyone that has experience. A noticeable spot has formed on one of the smaller leaves and before I makes changes I want to know how to proceed. Thank you for any help!

Certified GKH Gardening Expert
It is bacterial spot. Determining which one will likely require a microscope, but killing it will be easy.
Most bacterial infections will respond well to fungicides. This article will help:
https://www.gardeningknowhow.com/garden-how-to/info/homemade-fungicide.htm
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
Keep in mind that these plants will tolerate things on the drier side. Let the soil dry out, thoroughly, between waterings. Make sure that the top 1/3 of the soil is completely dry, at least.
https://www.gardeningknowhow.com/houseplants/philodendron/caring-for-philodendrons.htm
(The article poses the question whether your plant is a Philo, or Pothos... Your plant is, definitely, Philodendron.)