Sometimes second generation speakers will make up their own vocabulary as they go. For instance, instead of saying freno for the word brake, they may use breka. This is called Spanglish , and native speakers do cringe when they hear it. But this is not a Mexican phenomena, it happens just as much to children of immigrants from other nations. Another Spanglish phenomena, is not using the correct gender with the appropriate word.
Every noun has a gender in Spanish.
The exceptions are few so it pays to learn them. Little by little children learn vocabulary and only much later do they learn reading and grammar. Learning another language needs to be fun, otherwise, it is hard to stay committed. We need to celebrate small achievements. In contrast, I once spoke to the Spanish teacher of one of my high school children in Spanish, only to be answered in English.