“Sevilla” or “llamarse” are words that contain the letter “elle” (Ll). English speakers have problem to pronounce this letter. The reason is that the sound for letter LL is [ʎ], that does not naturally occur in English.
Properly the letter “LL” [ʎ] has a different pronunciation that the letter “Y” [ʤ] in Spanish.
In our class, I said that is very common say letter “ll” with the same pronunciation that “y”. This is known as yeísmo, and this is prevalent in most of Latin America (except Bolivia, Perú and Paraguay) and parts of Spain. In Spain yeísmo is widespread among the younger generation.
So the question is: how do I need pronounce letter “ll” in Spanish? The answer is complicate. Yeísmo is said by millions of Spanish speakers, so probably the best way is pronounce “ll” as a “y” in Spanish and it is the easiest way for an English speaker (non for academic purposes). Nowadays, the general rule is for the y/ll phonological opposition to be disappearing quickly all throughout Spain.
For example, notice the different sounds:
Now listen how I say the words “Sevilla” and “Marbella” with yeísmo.