The term "Congress" has several meanings depending on its context.
1) In a general sense, Congress refers to a legislative body in government that makes laws for a country or region. This is the most common use of the word and applies to many countries around the world including the United States, where it specifically refers to the two houses of the U.S. federal legislature - the Senate and House of Representatives.
2) In another context, Congress can refer to an organized meeting or conference of people with a shared interest or profession. For example, there may be a medical congress that brings together doctors from around the world to discuss advancements in their field.
3) Finally, "Congress" could also refer to a group of birds such as crows or sparrows.