The use of a double "c" in Lección
Is the double "c" in lección an exception to the rule that only "r" and "l" are doubled in Spanish?
3 Answers
CC is a common double letter combination in Spanish- the two c’s are pronounced separately, the first hard, the second soft:
https://www.cliffsnotes.com/study-guides/spanish/spanish-ii/spelling-and-pronunciation/consonants
Spanish, on the other hand, does not have many words with double consonants of the same consonant letter. You can find exceptions to this rule, however, with words containing ll, rr, cc, and nn; for example, diccionario, carro, connotación, and llave.
There are some important exceptions to the “no double letter” rule. The ll that occurs in Spanish is technically not a double l but rather a single letter that is pronounced like the consonant y in “yellow.”
Another letter in Spanish that looks like a double letter is the rr. This letter is intended to elicit the rolling sound that is difficult for many who are learning Spanish as a second language. You should roll your tongue when you see the letter rr within a word, or when a single r is the first letter of a word.
The only true double consonant in Spanish occurs when two c's are used to produce the x sound. In words like diccionario and acceso the first c is hard because it is followed by a consonant and the second c is soft because it is followed by i or e.
The nn is very rare (nm is much more common) but I do rarely see it.
Here's a link to an older post with everything you could possibly want to know about this subject--- and MORE. 
Link to Article about Words with Unusual Spelling
What a wonderful and very quick answer to my question. This is so helpful, as I have been studying Spanish for less than 1 week! I appreciate your help.
