The reference — the transcription keeps θ for c and z, x for j, and a d that softens to ð between vowels. The one thing added here is the merger that has already happened for nearly all speakers under fifty: ll has become y.
Where: central and northern Spain; the broadcast standard
The way in: Keep θ for every c and z and give every syllable the same weight.
Try a word
Anything the spelling engine can transcribe, the accent can move. Slow it down to hear the shape.
Reference
→
Castilian
Which rules fired
Nothing moved — this word has none of the sounds this accent changes.
Melody and rhythm
Even, syllable-timed rhythm — every syllable gets nearly the same length, which is what makes Spanish sound fast to an English ear. Falling intonation on statements, a clean rise on yes/no questions.
What moves, one rule at a time
In the order the mouth applies them. Every before-and-after is playable — click the IPA. The pattern is the rule as the engine runs it, for the curious.
Consonants
ll and y become one sound
ʎ → ʝ
How: Say y as in 'yes'. The tongue does not touch the roof of the mouth along the sides.
Yeísmo. The palatal l of the spelling survives only in parts of the north and the Andes; everywhere else it has become the y of 'yo'.