In a relational database, a row or "record" or "tuple", represents a single, implicitly structured data item in a table.
A database table can be thought of as consisting of rows and columns.
Columns might represent things like company name, address, etc.
The row is then interpreted as a relvar composed of a set of tuples, with each tuple consisting of the two items: the name of the relevant column and the value this row provides for that column.
Each column expects a data value of a particular type.