Replacing English words in a string with their Spanish equivalents by dictionary lookup
Problems

not properly handling words, just substrings. Currently, you are using str.replace() that would replace substrings in a string, not complete words, which means that it would behave incorrectly when your replacement is a part of another word - e.g. &quot;Cheese&quot; would be replaced from &quot;Cheesecake&quot; becoming &quot;Quesocake&quot;
just a single substring is replaced. you have that break statement which basically stops all the replacements after the first one occurred
handling words in different cases. You are also not properly handling the titled or upper-cased words