The plant leaf shows large dark brown/black patches with dry, crispy edges. This is usually caused by one or more of these problems:

• Too much direct sunlight (leaf burn)
• Overwatering causing root stress
• Fungal/bacterial leaf rot
• Poor drainage or water staying in the pot
• Sudden heat exposure

What I notice from the image:

• The damaged areas are dry and burnt-looking, not soft or mushy.
• The potting soil looks quite wet/dense.
• The plant seems kept near a wall with limited airflow/light balance.

What you should do:

1. Remove damaged leaves
   Cut the heavily blackened leaves using clean scissors. The damaged part will not recover.
2. Check soil moisture
   • If soil feels wet for many days, reduce watering.
   • Water only when the top 1–2 inches of soil become dry.
3. Improve drainage
   Make sure the pot has drainage holes. Avoid water collecting at the bottom.
4. Avoid harsh direct afternoon sun
   Keep the plant in bright indirect light for a few weeks.
5. Check roots if condition worsens
   If stems become soft or smell bad, roots may be rotting. Repot into fresh, well-draining soil.
6. Fungus prevention
   You can spray a mild fungicide or neem oil once weekly if black spots continue spreading.

The plant still has green healthy sections, so it can recover with proper care.