Why do Brazilians understand simple Spanish?

Spanish and Portuguese are the two closest languages ??in the Latin family of languages ??(French, Spanish, Portuguese, Italian and Romanian). The grammar of Spanish and Portuguese is very similar. Except for the different forms of articles, other aspects are very similar. So, once you understand Spanish, you won’t have to worry about Portuguese. I once translated a Portuguese engineering technology paper more than 20 years ago. It is funny to say that when the leader brought this Portuguese paper, he thought it was in French, so he came to me. I looked at it and found that I could guess most of the contents, so I continued. But at the time, I really didn’t know that the article I was handed was in Portuguese. I translated it based on my French and Spanish skills. Of course, it is not something that can be done casually. I made a statistical summary of the frequency of word ending changes, and then arranged them according to the rules of general linguistics, thus roughly analyzing the grammatical structure and judging based on my own grammatical guesses. A draft table of grammatical rules was produced and then translated. The word part is judged and logically inferred based on the root of the word. These are the categories of general linguistics, and it is more complicated to expand them. Just wanted to tell you that Spanish and Portuguese are really close.