For equivalent English sounds, you can find the Japanese じょ sound in certain names and words:
You can also find the Japanese よ sound in certain words:
Here is an example of a phrase in Japanese that uses longer forms for each of the sounds じょ and よ on this website: JOUYOU KANJI
On that page is an audio recording of someone named "akitomo" speaking a phrase that includes both the じょ and the よ sounds: "JOUYOU KANJI". (In that recorded phrase, can you hear the difference between the first part "JOU" and the second part "YOU"?)
As your native language is Spanish, you could almost think of Brazilian Portuguese pronounciation for (at least some cases of) the letter "j" when it comes to pronouncing the じょ sound, as well. Do keep in mind, however, that the Brazilian Portuguese pronunciation might be slightly different (i.e. more of a softer "j" sound) than the Japanese pronunciation of じょ.