Nel / Nello
What is nel/nello?
Prepositional Articles.
What is Prepositional Articles?
In short when Preposition comes before articles in a sentence and nothing being between them they combined together and become Prepositional Articles.
In other sentence:
In italian for using "in" we use "in" but if we need to use "in" with article "the" then we use nel/nello.
When use nel and when use nello:
There's no difference in meaning. You use "nello" when the following masculine word starts with "s + consonant", "z", "gn", "ps" or "pt". Otherwise, you use nel.