A person can spend years in a classroom or untold hours taking in-home or online courses learning to speak Spanish (or any other foreign language) and think they've completely mastered the challenge.Then visit or relocate to Mexico, Argentina, Puerto Rico, or another Spanish-speaking country and find out that they have only scratched the surface in truly being able to comprehend what is being said. Even some Spanish translation services have difficulty piecing the words together in a way that makes sense or is accurate.
Native speakers of any language have different dialects that are based on which part of the region those speakers come from, often substituting words or using slang phrases for some common words. This can be seen most clearly in the way Americans use slang to convey expressions that may not be understood by other English-speaking natives. For example, people raised in the South use terms such as "y'all" and "down yonder" and "I reckon," all of which are perfectly clear to other Southerners, but may not be quite so expressive to people from New York or someone from another country.
Sometimes slang can be such a barrier to effective communication and comprehension that one man spent years creating guides to understanding slang expressions in various Spanish-speaking countries, with each country having its own innate varieties of slang. The use of Spanish translation services, either through a company or via online translation, would only have partially enabled full comprehension of what was being said in general conversation.
However, all is not lost if you wish to employ Spanish translation services to decode foreign conversations, papers, and documents. Many employ native speakers of the tongues they translate, as well as people who mastered the language through education, and this can prove invaluable in wading through the dialects and "slanguage" to uncover the real message.