Questions & Answers about Вечером я выключаю телевизор и читаю книгу.
Вечером is the instrumental case of вечер (evening).
In this sentence it doesn’t really mean with the evening; in modern Russian the instrumental is often used to express time when something happens, so вечером means in the evening.
This is a set pattern for parts of the day:
- утро → утром = in the morning
- день → днём = in/at daytime
- вечер → вечером = in the evening
- ночь → ночью = at night
So Вечером я… literally is In the evening I…
Another related form you’ll often see is по вечерам = in the evenings / in the evenings generally, emphasizing repeated action over many evenings, while вечером can be either today’s evening or a general evening context, depending on context.