Hi! Miguel from Spanish Input here.
Textbooks tell you that the Spanish Y/LL is pronounced as the Y in "yes", "beyond" or "yellow" in most countries. But that's not true. In reality, the most common pronunciation worldwide is a voiced palatal fricative. The phonetic symbol for this sound is [ʝ], a lower case J with a loop.
If you're a member of the Spanish Input channel on YouTube, you can watch a detailed lesson of the [ʝ] sound with tons of exercises here: https://youtu.be/CJlI0wUuTNg
You can join as a member for just $4.99.
Let me share some information from this lesson. Of course, you'll understand this 100x better with sound in the actual lesson.
So, what is a "voiced palatal fricative"? "Fricative" means it's a sound produced with friction; like sandpaper on wood. "Palatal" means it's produced in the hard palate, the bony part of the roof of your mouth.
In this graphic you can see the tongue position for the [ʝ] sound and how it compares to the tongue position for the Spanish [i] sound:
As you can see, in both cases the tongue moves towards the hard palate. The key difference is how much space there is for the air to pass. When we pronounce the Spanish [i] vowel, and when you pronounce the Y in "yes", there is more space for air to pass. Therefore, there is no friction.
On the right hand, however, you can see that the air goes through a very narrow space when we pronounce the Spanish [ʝ] consonant. This produces a friction sound. This is why it's called a "fricative".
When I tell my students to pronounce words like "ella" and "apoyo" with friction, the #1 mistake is to pronounce the S in "pleasure". However, the tongue position is very different:
As you see, when you pronounce the [ʒ] in "pleasure" both the tip of the tongue and the blade are in the back of the upper teeth's gums, aka "the alveolar ridge". This tongue position produces a sound considered "strident" or excessively noisy in most Spanish-speaking countries. The [ʝ] sound, in contrast, is softer, and it's produced further back in your mouth. The tongue tip is usually found next to your lower teeth. A trick I use is to tell the learner to touch the lower teeth with the tip of the tongue. This way it's harder to pronounce the harsh [ʒ] sound in "pleasure" and it's easier to produce the proper [ʝ] sound.
So, do you really need to produce the proper [ʝ] sound? Yes, you do. This will make it easier to understand you and you'll sound less "gringo".
Can't you just get away with using the English Y? No. If you try to use the English Y, you might end up producing a sound that is too soft. It can even disapperar when it's next to an [e] and especially when it's next to an [i]. "Comillas" (quotation marks) pronounced with an English Y can sound like "comías" (you used to eat) to a Spanish speaker.
Other possible confusions:
Villa → Vía
Pillo → Pío
Milla → Mía
If you ask a taxi driver to take you to "Villa Flores" and you don't use the Spanish [ʝ] sound, you might end up in "Vía Flores" (Flores roadway).
Learning the proper pronunciation of the Spanish [ʝ] sound makes it easier to understand you. And if people have to do less effort to understand you, they're less likely to switch to English.
So, again, here's the link to the lesson:
If you're not a member of my channel yet, join as a member here:
https://www.youtube.com/spanishinput/join
Happy learning,
-Miguel