Questions & Answers about Вечером мне хочется, чтобы в доме был порядок.
Russian often uses the instrumental case to express time when something happens: утром, днём, вечером, ночью, зимой.
So вечером literally means in the evening / in the evenings (depending on context), and it’s a fixed, very common pattern.
By itself, вечером is ambiguous: it can be either in the evening (at evening time) or (usually) in the evenings, depending on context.
If you want to be clearly habitual, Russian often uses по вечерам = in the evenings (as a habit).
If you want clearly “tonight/this evening,” you might use сегодня вечером.
хотеться works like a “feeling/wanting happens to me” construction. The experiencer is in the dative: мне = to me.
So мне хочется is closer to I feel like… / I have the desire… than a direct, deliberate я хочу.