If you've ever tried to have a conversation in a foreign language, you know it can be pretty tough, and it takes practice! Even if you're speaking your native language, it can be confusing if the other people are talking about a topic you have no background in. In the 'research conversation', much the same is true... those that have spent years studying your topic can seem to be speaking an entirely different language. Likewise, many assumptions are made about what background everyone in the conversation has... most research discussions don't start back at the basics, but give a brief introduction and assume a lot of common prior knowledge.
This assumed background knowledge can include:
Learning the lingo or specialized jargon of a field isn't always as simple as consulting a general dictionary. Often, words have particular meanings in your field that will only be defined in more specialized dictionaries.
Other aspects are also assumed when you read a scholarly article (or write one!) as basic knowledge within the field. These may be things discussed in textbooks or encyclopedias, for example.
Every discipline has its own methods of conducting research. These can be experimental procedures described in the 'methodology' section of research articles, basic ways of conducting field research, or even broad theoretical frameworks.