Too much water! Let the plant rest for a few days without watering, then it will recover.
You could also dim the light if you have a dimmer.
Here are some other things you can do to help your plant recover from overwatering:
Check the drainage holes: Make sure the pot has drainage holes in the bottom. If it doesn't, you can drill some holes yourself. This will allow excess water to drain out of the pot, which will help to prevent the roots from sitting in water.
Repot the plant: If the pot is too small, the roots may be crowded and this can also contribute to overwatering. Repot the plant in a pot that is one size larger using a fresh potting mix.
Aerate the soil: Use a chopstick or other tool to gently poke holes in the soil around the plant. This will help to improve aeration and drainage.
Increase air circulation: Move the plant to a location with good air circulation. This will help to prevent the soil from staying too wet.
With a little care, your plant should be able to recover from overwatering. Just be sure to avoid watering it again until the soil is completely dry.
Here are some additional tips for watering your plants:
Water deeply but infrequently: It is better to water your plants deeply once a week or so than to give them a little water every day. This will help to encourage the roots to grow deep into the soil.
Water in the morning: Watering in the morning will give the plant time to absorb the water before the heat of the day causes it to evaporate.
Check the soil before watering: Before you water your plant, stick your finger into the soil up to your first knuckle. If the soil feels dry, it's time to water. If the soil feels moist, wait a few days and check again.
Don't water on a schedule: The amount of water your plant needs will vary depending on the type of plant, the size of the pot, the time of year, and the humidity. Don't water your plants on a schedule; instead, check the soil and water when needed.
By following these tips, you can help to keep your plants healthy and prevent them from being overwatered.