What is this tall plant?
This is a houseplant called Dieffenbachia or dumb-cane. Such beautiful foliage.
The like bright filtered light in all seasons, except winter, when they can have direct sun at the brightest window you have. (They can spend the summer outdoors, but not in direct sun, and keep it watered.)
They like normal room temps, but will like warmth and can't take temps below 60F.
We'd suggest upping the humidity around them by filling a saucer with pebbles and water, and the plant on top.
Water enough each time so that the entire soil mixture is moist, and water drains from the bottom of the pot.It can sit in the water for several minutes, but don't let it stand in water over time. Allow the top inch of the soil to dry out (you can test with your finger) before watering again. They like a standard houseplant fertilizer no more often than every two weeks, but will do well without it too.
You might consider repotting to a larger pot next spring, or even taking the top cutting and rooting it to refresh the plant.