There are two ways to learn - one method is through imitation, ie listening to a recording over and over and over until it sticks in your head. I have memories of this from the school choir having to sing in
German and Latin.

To learn from text/sheet music etc it is a big help to learn the alphabet of the language - ie difference in pronunciation. - phrasebooks often provide an English equivalent to how words are pronounced, but that is only an approximation, so it is worth the effort to learn the proper pronunciation.