What does the spanish word Callao mean?

There exist contraction in Spanish, just like they exist in English. Some spanish Words though do not include the apostrophe when letters are removed.

Any spanish Word that ends in "ado" can occasionally have the 'd' removed to make it sound better. This often happens in Spanish reggaeton (a type of spanish rap) to make the song have better rythem.

Callao therefore would actually be "callado" which is the spanish Word for 'quiet'.