Чудесно is one of the words in Russian language that reflects a feeling of satisfaction and pleasure. It comes from the word «чудо», which means wonder or miracle. It is close in meaning to «очень хорошо», "very well/good" and «отлично», "excellent." It is also used as an expression of consent. (source)

Although people still say it fairly often, it was more commonly used in classic literature. I can imagine «барышня», a "young lady" from one of Pushkin's works, exclaim:

A slightly distorted version of «чудесно» also appears in Lewis Carroll's «Алиса в Стране Чудес», "Alice in Wonderland". Russian translation of "curiouser and curiouser" is «всё чудесатее и чудесатее». Just as in English, it is an incorrect use of the word. The writer made it up to show that Alice was so surprised that she forgot the proper way of saying it.

When I was little, I would listen to "Alice in Wonderland" on our old vinyl record player and imagine how it would be to find myself there, meet the Cheshire cat or follow the white rabbit... Oh, how nice would it be to escape into Страна Чудес “Wonderland”!